Answer:
The answer is option 2.
Step-by-step explanation:
First, you have to find the length of CD using Tangent Rule, tanθ = opposite/adjacent:
[tex] \tan(θ) = \frac{oppo.}{adj.} [/tex]
[tex]let \: θ = 48[/tex]
[tex]let \: oppo. = cd[/tex]
[tex]let \: adj. = ad = 110[/tex]
[tex] \tan(48) = \frac{cd}{110} [/tex]
[tex]cd = 110 \tan(48)[/tex]
[tex]cd = 122.17 \: feet[/tex]
Next, you have to find the length of BC using Sine Rule:
[tex] \sin(θ) = \frac{oppo.}{hypo.} [/tex]
[tex]let \: θ = 65[/tex]
[tex]let \: oppo. = cd = 122.17[/tex]
[tex]let \: hypo. = bc[/tex]
[tex] \sin(65) = \frac{122.17}{bc} [/tex]
[tex]bc = \frac{122.17}{ \sin(65) } [/tex]
[tex]bc = 134.8 \: feet \: (near.tenth)[/tex]
Answer:
[tex]\boxed{134.8 \: \mathrm{ft}}[/tex]
Step-by-step explanation:
Let’s take triangle ACD.
Find length CD.
tan θ = [tex]\frac{opposite}{adjacent}[/tex]
tan (48) = [tex]\frac{CD}{110}[/tex]
110 tan (48) = CD
CD ≈ 122.167
Let’s take triangle BCD.
Find length BC.
sin θ = [tex]\frac{opposite}{hypotenuse}[/tex]
sin (65) = [tex]\frac{122.167}{BC}[/tex]
BC = [tex]\frac{122.167}{sin(65)}[/tex]
BC ≈ 134.796
Pls answer the 9th question...plsss fast
Answer:
i) x = 65° ii) x = 60° iii) x = 34°
y = 50° y = 80° y = 124°
Step-by-step explanation:
i) x = 180-115= 65°
y = 65+65= 130
= 180-130= 50°
ii) x = 90+30= 120
180-120= 60°
y = 60+20= 80
180-80 = 100
180-100= 80°
iii) y = 34+90= 124
x = 180-124= 56
56+90= 146
180-146= 34°
I hope this helped, mark me brainliest please :)
Which letter has a line of symmetry?
Answer:
D. all of the above
Step-by-step explanation:
All the letters from the options have a line of symmetry.
The surface area of a solid is 10 square feet. The dimensions of a similar solid are
three times as great as the first. The surface area of the new solid in square feet
is...
PLEASE urgent
Answer:
90 ft²
Step-by-step explanation:
Given the sides of similar figures in the ratio a : b, then
ratio of areas = a² : b²
Here ratio of sides = 1 : 3 , thus
ratio of areas = 1² : 3² = 1 : 9
That is the surface area of the new solid is 9 times the first
SA = 9 × 10 = 90 ft²
The total surface area of the new solid in square feet is 90 square feet
Let the solid be a cube.
The surface area of a cube = 6L²
L is the length o the cube;
If the surface area of a solid is 10 square feet, then;
10 = 6L²
L² = 10/6
L = √10/6
If the dimensions of a similar solid are three times as great as the first, then;
New length Ln = 3√10/6
Total surface area of the new solid = 6Ln²
Total surface area of the new solid = 6(3√10/6)²
Total surface area of the new solid = 6(9*10/6)
Total surface area of the new solid = 6(90/6)
Total surface area of the new solid = 90 square feet
This shows that the total surface area of the new solid in square feet is 90 square feet
Learn more here: https://brainly.com/question/23756628
A researcher wants to obtain a sample of 30 preschool children consisting of 10 two-year-old children, 10 three-year-old, and 10 four-year-old children. Assuming that the children are obtained only from local daycare centers, this researcher should use ____ sampling.` Cluster probability quota simple random stratified random
Answer:
Quota Sampling
Step-by-step explanation:
Quota Sampling is a non-probability sampling method in research, where the researcher forms subgroups of individuals who are representative of the entire population through random selection. Quota sampling is often used by researchers who want to get an accurate representation of the entire population. It saves time and money especially if accurate samples are used.
In the example given above, where the research creates subgroups of 30 pre-school children by dividing them into 10 two-year-old children, 10 three-year-old, and 10 four-year-old children, he has applied the quota sampling. These subgroups would give a proper representation of the preschool children in local daycare centers.
If Line LK = 16, find the length of Line JK.
Answer:
JK = 16√2
Step-by-step explanation:
This triangle is a special case right triangle, where you have 1 90-degree angle and 2 45-degree angles. The sides that correspond to the 45-degree angles are scalable by 1 and the hypotenuse is scalable by √2. Sometimes these are called 1-1-√2 triangles, describing the measurements of the sides.
Since this has a side of 16, the hypotenuse will be 16√2.
Cheers.
Marguerite wants to rent a carpet cleaner. Company A rents a carpet cleaner for $15 per day. Company B rents a carpet cleaner for $100 per week, with a one-time fee of $5. The following functions represent the rate structures of the two rental companies: x = the number of weeks Company A f(x) = 15(7x) Company B g(x) = 100x + 5 The function h(x) = f(x) – g(x) represents the difference between the two rate structures. Determine which statements about h(x) and about renting a carpet cleaner are true. Check all that apply. h(x) = 5x – 5 h(x) = 5x + 5
Answer:
If Marguerite rents for 2 weeks, it will cost her less if she rents from Company B
If Marguerite rents for 1 week, it will cost her the same at either company
h(x) = 5x - 5
Step-by-step explanation:
Marguerite wants to rent a carpet cleaner. Company A rents a carpet cleaner for $15 per day. Company B rents a carpet cleaner for $100 per week, with a one-time fee of $5. The following functions represent the rate structures of the two rental companies: x = the number of weeks Company A f(x) = 15(7x) Company B g(x) = 100x + 5 The function h(x) = f(x) – g(x) represents the difference between the two rate structures. Determine which statements about h(x) and about renting a carpet cleaner are true. Check all that apply. If Marguerite rents for 2 weeks, it will cost her more if she rents from Company B. If Marguerite rents for 2 weeks, it will cost her less if she rents from Company B. If Marguerite rents for 1 week, it will cost her the same at either company. If Marguerite rents for 1 week, it will cost her more if she rents from Company A. h(x) = 5x – 5 h(x) = 5x + 5
Answer: Company A rents a carpet cleaner for $15 per day. Company B rents a carpet cleaner for $100 per week, with a one-time fee of $5. In one week there are 7 days, therefore in x weeks the cost of rentals are given below:
For company A: f(x) = 15(7x)
For company B: g(x) = 100x + 5
h(x) = f(x) – g(x) represents the difference between the two rate structures.
h(x) = f(x) - g(x) = 15(7x) - (100x + 5)
h(x) = 105x - 100x - 5
h(x) = 5x - 5
If Marguerite rents for 2 weeks:
The cost for company A = 15(7x) = 15(7 × 2) = $210
The cost for company B = 100x + 5 = 100(2) + 5 = 200 + 5 = $205
If Marguerite rents for 2 weeks, it will cost her less if she rents from Company B
If Marguerite rents for 1 weeks:
The cost for company A = 15(7x) = 15(7 × 1) = $105
The cost for company B = 100x + 5 = 100(1) + 5 = 100 + 5 = $105
If Marguerite rents for 1 week, it will cost her the same at either company
Answer:
If Marguerite rents for 2 weeks, it will cost her less if she rents from Company B.
h(x) = 5x + 5
those are the answers on edge
Step-by-step explanation:
Stephanie left Riverside, California, driving her motorhome north on Interstate 15 towards Salt Lake City at a speed of 56 miles per hour. Half an hour later, Tina left Riverside in her car on the same route as Stephanie, driving 70 miles per hour. Solve the system {56s=70ts=t+12 for t to find the value of s, the number of hours Stephanie will have driven before Tina catches up to her.
Answer:
The number of hours Stephanie will have driven before Tina catches up to her is 2.5 hours
Step-by-step explanation:
Given:
56s=70t
s=t+1/2
Solution
56s=70t
s=t+1/2
Substitute s=t+1/2 into 56s=70t
56s=70t
56(t+1/2)=70t
56t+28=70t
28=70t - 56t
28=14t
Divide both sides by 14
28/14=14t/14
2=t
t=2
Recall,
s=t+1/2
s=2+1/2
=4+1/2
s=5/2
Or
s=2.5 hours
look at the picture find the value of z
Answer:
Z=7.9
Step-by-step explanation:
20.4 + 20.4 = 40.8
56.6 - 40.8 = 15.8
15.8/2 = 7.9
Answer:
z=7.9 cm
Step-by-step explanation:
So, what we have to do is gather all the information we already have. The length of the rectangle is 20.4 cm, and the perimeter is 56.6. To find the perimeter, you always add all the sides up. So 20.4+20.4 is 40.8. since 4+4 is 8, and 20+20 is 40. Then, you subtract that from the perimeter to get what is 2z(both sides). 56.6-40.8 is 15.8. So we know 2z is 15.8. To find z, we divide 15.8 by 2 which is 7.9. You can do this with a calculator or write it down.
z=7.9 cm
If f(x)=k (square root)2+x, and f^-^1 (-15)=7, what is the value of k
There's a bit of ambiguity in your question...
We know that [tex]f^{-1}(-15)=7[/tex], which means [tex]f(7)=-15[/tex].
I see three possible interpretations:
• If [tex]f(x)=k\sqrt2+x[/tex], then
[tex]f(7)=-15=k\sqrt2+7\implies k\sqrt2=-22\implies k=-\dfrac{22}{\sqrt2}=11\sqrt2[/tex]
• If [tex]f(x)=k\sqrt{2+x}[/tex], then
[tex]f(7)=-15=k\sqrt{2+7}\implies -15=3k\implies k=-5[/tex]
• If [tex]f(x)=\sqrt[k]{2+x}[/tex], then
[tex]f(7)=-15=\sqrt[k]{2+7}\implies-15=9^{1/k}\implies\dfrac1k=\log_9(-15)[/tex]
which has no real-valued solution.
I suspect the second interpretation is what you meant to write.
Solve for x: |x| − 8 = −5 (2 points) A. x = −13 and x = −3 B. x = 3 and x = −3 C. x = 3 and x = 13 D. No solution
Answer:
x = 3 and x = -3
Step-by-step explanation:
/x/ - 8 = -5
Add 8 to both sides
/x/ -8 + 8 = -5 +8
/x/ = 3
/ x / will be always positive as it is absolute value of x. So, x = 3 & x= -3
A town currently has a population of 1,000,000, and the population is increasing 6 percent every year
a) using standard function notation , next = nowx1.06, starting at 1,000,000 use p to denote current population, r for the rate of population growth, and t for the number of years explain answer
b)is the function you wrote in the previous task recursive or non recursive?
c)compare the benefits of representing a situation using a recursive function versus using a regular function
Answer:
a) [tex]1,000,000 \times (1.06)^{t}[/tex]
b) The function is recursive
c) The benefits includes;
1) Simplification of information
2) Faster data access
3) Lesser storage requirement
4) Good for forecasting
5) Simplifies information analysis.
Step-by-step explanation:
The given information are;
The current population = 1,000,000
The rate of increase of the population = 6%
a) With the standard function notation is [tex]P_f[/tex] = [tex]P_p[/tex] × [tex](1 + r)^{t}[/tex]
Where;
[tex]P_f[/tex] = Future population
[tex]P_p[/tex] = Present population
r = Rate of population increase
t = The number of years
Therefore, we have;
[tex]P_f[/tex] = 1,000,000 × [tex](1 + 0.06)^{t}[/tex] = 1,000,000 × [tex](1.06)^{t}[/tex]
The population increases by a factor of [tex](1.06)^{t}[/tex] given the number of years, t
b) The function is recursive as it takes account of the number of years and the previous population to calculate the future population
c) The benefits includes;
1) Simplification of the relationship of a given data with time
2) Provides a more faster way to access data that is recursive than using complex regular function with more variables
3) Reduces data storage space for statistical calculations as several particular data can be accessed using one function
4) Provides improved forecasting
5) Enables detailed information analysis.
A bicycle is on sale price for $300 it can be brought through a hire purchase with a deposit of $60 and 10%
interest the outstanding balance, to prepaid in 10 monthly installments calculate:
a)the amount of each monthly instalment
b)the total cost of buying the bicycle by hire purchase
Answer:
a) $26.4
b) $324
Step-by-step explanation:
Hire purchase is the purchase of an item which can be paid instalmentally.
The bicycle costs $300 for an instant purchase.
For a hire purchase, a $60 deposit must be made and the rest paid instalmentally over 10 months. An interest of 10% is included in the outstanding balance
The outstanding balance after paying deposit= $300 - $60 = $240
Hence, 10% of 240 = 10/100 × 240 = 24
An interest of $24 is added.
Therefore, a total of $240 + $24 = $264 will be paid for the next 10 months.
a) Hence, the amount to be paid in instalment each month is $264/10 = $26.4
b) the total cost of buying the bicycle by hire purchase= deposit amount + instalment price
= $60 + $264
= $324
Hence, a total of $324 will be paid for the bicycle by hire purchase.
N.B: $300 is the sale price + $24 interest
How many times larger is 5 × 106 than 5 × 102?
PLEASE HELP !
Divide the largest one by the smallest one : for example, the number 4 is 42=2× larger than the number 2.
Indeed, If you multiply 2 by 42 you'll get 4.
Of course, if a number is n× larger than another, then this other is n× smaller than the first one.
It will of course work with floating point : 0.6×10.6≈0.6×1.6667=1 so 1 is ~1.6667 times larger than 0.6 while 0.6 is ~1.6667 smaller than 1.
plz mark me as the Brainleist plz
If approximately 10% of people are left-handed, how many lefties would you expect in a high school graduating class of 424
Answer:
42
Step-by-step explanation:
P(left) = 0.10
Expected number of lefties among high school grads of 424
= 424 * 0.10
= 42 (to the nearest person)
Answer:
you do 20% of 424
1 0% of 424 =42.4
you could round it to 42
At a birthday party, each child is given some chocolates. There are five 5-year-olds, five 6-year-olds and five 7-year-olds at the party. If each child receives three times as many chocolates as their age in years, how many chocolates are given out altogether?
Answer: 270 chocolates
Step-by-step explanation:
Given the following :
Number of 5-year Olds = 5
Number of 6-year Olds = 5
Number of 7-year Olds = 5
Number of chocolates received by each child = 3 times as many chocolate as their age.
Number of chocolates received by 5-year Olds = 3 × 5 = 15 chocolates
Number of chocolates received by 6-year Olds = 3 × 6 = 18 chocolates
Number of chocolates received by 7-year Olds = 3 × 7 = 21 chocolates
Total Number of chocolates received by 5-year Olds = 5 * 15 = 75 chocolates
Total Number of chocolates received by 6-year Olds = 5 * 18 = 90 chocolates
Total Number of chocolates received by 7-year Olds = 5 * 21 = 105 chocolates
Totak number of chocolates altogether :
(75 + 90 + 105) = 270 chocolates
figure out if the equation is inverse or direct
Answer:
A. Inverse variation
B. Direct variation
C. Direct variation
D. Inverse variation
Hope this helps you
Jack deposited 200$ in his savings account in 1$ and 5$ bills. If he deposited 136 bills, how many 5$ bills did he deposit?
Answer:
He deposited 16 $5 bills.
Step-by-step explanation:
State your variables
let x be the number of $1 bills
let y be the number of $5 bills
Create a system of equations
x + 5y = 200 (eq'n 1 -- for amount of money)
x + y = 136 (eq'n 2 -- for number of bills)
Solve the system for y
I will solve using substitution. Rearrange eq'n 2 to isolate variable x.
x + y = 136
x = 136 - y (eq'n 3)
Substitute eq'n 3 into eq'n 1.
x + 5y = 200
136 - y + 5y = 200
136 + 4y = 200
4y = 64
y = 16
Solve for x to check answer
Substitute y = 16 into eq'n 2.
x + y = 136
x + 16 = 136
x = 120
Substitute x = 120 into eq'n 1.
x + 5y = 200
120 + 5(16) = 200
120 + 80 = 200
200 = 200
LS = RS Both sides are equal, so the solution is correct.
Therefore, Jack deposited 16 five dollar bills.
Resolve into factors.
a)x4-5x2y2+4y4
Answer:
(x - y)(x + y)(x - 2y)(x + 2y)
Step-by-step explanation:
Given
[tex]x^{4}[/tex] - 5x²y² + 4[tex]y^{4}[/tex]
Consider the factors of the coefficient of the [tex]y^{4}[/tex] term (+ 4) which sum to give the coefficient of the x²y² term (+ 5)
The factors are - 1 and - 4 , thus
[tex]x^{4}[/tex] - 5x²y² + 4[tex]y^{4}[/tex]
= (x² - y²)(x² - 4y²)
Both of these factors are differences of squares which factor in general as
a² - b² = (a - b)(a + b) , so
x² - y² = (x - y)(x + y)
x² - 4y²
= x² - (2y)² = (x - 2y)(x + 2y)
Hence
[tex]x^{4}[/tex] - 5x²y² + 4[tex]y^{4}[/tex]
= (x - y)(x + y)(x - 2y)(x + 2y) ← in factor form
What is the name of the method for drawing a trend line for the data in a scatterplot in which an oval is drawn around all the points in the scatterplot except the outliers?
a.the oval method
b.the divide-center method
c.the area method
d.the regression calculator method
ty if you answer! :3
Answer:
c.the area method
Step-by-step explanation:
A scatterplot is a plotting of data that represents the relationship between the two variables that should be numerical in nature. The data points i.e to be shown in a horizontal and vertical axis represent that how much one variable affected by another variable.
In the area method, we plot a data and then draw a shape which can be in oval but it does not include the outliers but the other methods like oval method, divide center method, regression calculator includes the outliers
Therefore the option c is correct
Answer:
c.the area method
Step-by-step explanation:
c.the area method c.the area method c.the area method c.the area methodc.the area methodc.the area methodc.the area method c.the area method c.the area method c.the area method c.the area method c.the area method
Find the angle of rotation about the center of the regular pentagon that maps A to D.
Answer:
216
Step-by-step explanation:
Find each angle's value. This is a pentagon, so 360/5 = 72. Now, to get from A to D, you have to go 3 spaces counter-clockwise. This'll get you 72 x 3 = 216.
Answer:
216
Step-by-step explanation:
Find each angle's value. This is a pentagon, so 360/5 = 72. Now, to get from A to D, you have to go 3 spaces counter-clockwise. This'll get you 72 x 3 = 216.
At the toy store, you could get 4 board games for $25.84. Online, the price for 5 board games is $32.15. Which place has the highest price for a board game?
Answer:
The board game store
Step-by-step explanation:
Just divide the store price by 4 and online by 5
Answer:
Toy store
Step-by-step explanation:
Let's find the unit rates for the toy store and the online store. To find the unit rate, divide the price by the number of board games.
price/board games
Toy Store
price/board games
The toy store sells 4 board games for $25.84
$25.84 / 4 board games
25.84/5
6.46
Online Store
price/ board games
The online store sells 5 board games for $32.15
$32.15 / 5 board games
32.15/5
6.43
At the toy store, a board game costs $6.46. Online, it costs $6.43.
6.46 is greater than 5.43, therefore, the toy store has the higher price for a board game.
Use the cubic model y = 10x3 − 12x to find the value of y when x = 9.
Answer:
7182
Step-by-step explanation:
All you shoud do is to replace x by 9
● y = 10 * 9^3 -12*9
● y = 7182
rectangleabcd is graphed in the coordinate plane. the following are the vertices of the rectangle:a(2,−6),b(5,−6),c(5,−2) andd(2,−2) What is the perimeter of rectangle
ABCd?
Answer:
14
Step-by-step explanation:
The rectangle has side lengths of 3 and 4. There are two of each length, so the total length of all the sides is ...
P = 2(l +w) = 2(4 +3) = 2(7)
P = 14 . . . . units
Which of the following statements is true about the relation represented in the table? The data in the table is linear. The data in the table is nonlinear.
Answer:
Sacramento
Step-by-step explanation:
S 11+9+14+12+8=54
SF 11+8+8+9+12=48
The statement that is true about the information in the table is that the data is non-linear.
Which statement is true about the given table?
The easier way to study the table is by graphing it. Here we have the points:
(11, 11), (12, 9), (9, 8), (8, 8), and (14, 12).
The graph of these points can be seen below, there you can see that the data in the table is clearly non-linear, as we can't draw a line that contains the points on the table.
So the correct option is non-linear.
If you want to learn more about tables, you can read:
https://brainly.com/question/7301139
How many solutions does the equation 3x + 6 =- 1 - 3 + 4x have?
TWO
Zero
One
Infinitely many
Answer:
one solution
Step-by-step explanation:
3x + 6 =- 1 - 3 + 4x
Subtract 3x from each side
3x-3x + 6 =- 1 - 3 + 4x -3x
6 = -4+x
Add 4 to each side
6+4 = -4+4+x
10 =x
One solution
Answer:
The answer is one solution. Graph the line, and you will see that it is an infinite vertical line that goes through the x-axis at x=10. It only goes through the x-axis once, at x=10, so the answer is one solution.
Step-by-step explanation:
The answer is one solution. Graph the line, and you will see that it is an infinite vertical line that goes through the x-axis at x=10. It only goes through the x-axis once, at x=10, so the answer is one solution.
The canvas of a painting has an area of 64 ft2. What length of frame is needed for the border of the painting?
Answer:
8
Step-by-step explanation:
Assuming, the canvas has the shape of a square. By the square area formula we can derive its side:
[tex]S=l^{2}\\64=l^{2}\\l=\sqrt{64}\\ l=8\: ft[/tex]
Then Each side of the painting measures 8 feet, the length of frame must have 8 feet long, and the width is decided by the framer.
Answer:
The answer is C: 32 ft
Step-by-step explanation:
If you take the square root of the area of 64 ft ^2, you get 8. then it asks what is the length needed for the frame as in the entire frame. So you just have to multiply 8 by 4 which is the number of sides. Also, I got this right on the edg quiz.
George walks 1 mile to school. He leaves home at the same time each day, walks at a steady speed of 3 miles per hour, and arrives just as school begins. Today he was distracted by the pleasant weather and walked the first 1/2 mile at a speed of only 2 miles per hour. At how many miles per hour must George run the last 1/2 mile in order to arrive just as school begins today?
Answer:
George must run the last half mile at a speed of 6 miles per hour in order to arrive at school just as school begins today
Step-by-step explanation:
Here, we are interested in calculating the number of hours George must walk to arrive at school the normal time he arrives given that his speed is different from what it used to be.
Let’s first start at looking at how many hours he take per day on a normal day, all things being equal.
Mathematically;
time = distance/speed
He walks 1 mile at 3 miles per hour.
Thus, the total amount of time he spend each normal day would be;
time = 1/3 hour or 20 minutes
Now, let’s look at his split journey today. What we know is that by adding the times taken for each side of the journey, he would arrive at the school the normal time he arrives given that he left home at the time he used to.
Let the unknown speed be x miles/hour
Mathematically;
We shall be using the formula for time by dividing the distance by the speed
1/3 = 1/2/(2) + 1/2/x
1/3 = 1/4 + 1/2x
1/2x = 1/3 - 1/4
1/2x = (4-3)/12
1/2x = 1/12
2x = 12
x = 12/2
x = 6 miles per hour
Find the indicated area under the curve of the standard normalâ distribution; then convert it to a percentage and fill in the blank. Aboutâ ______% of the area is between zequals=minusâ1 and zequals=1 â(or within 1 standard deviation of theâ mean). About nothingâ% of the area is between zequals=minusâ1 and zequals=1 â(or within 1 standard deviation of theâ mean).
Answer:
68.26%
Step-by-step explanation:
The z score is a measure used in statistic to determine the number of standard deviations by which the raw score is above or below the mean. If the z score is positive then the raw score is above the mean and if it is negative then the raw score id below the mean. The z score is calculated using:
[tex]z=\frac{x-\mu}{\sigma}\\ where\ \mu \ is \ the\ mean, \sigma\ is\ the\ standard\ deviation\ and\ x \ is\ the\ raw\ score[/tex]
From the normal distribution table, Area between z equal -1 and z equal 1 = P(-1 < z < 1) = P(z < 1) - P(z < -1) = 0.8413 - 0.1587 = 0.6826 = 68.26%
About 68.26% of the area is between z = -1 and z = 1 (or within 1 standard deviation of the mean).
please help me with this
Answer:
see explanation
Step-by-step explanation:
2πr (230/360) = 2(3.142)(40) = 160.59 cm = circumference
160.59 = 2πr
base radius = 25.56 cm
Use pythagorean formula for semi-vertical height
40² = h² + 25.56²
h = 30.77 cm
volume = 1/3πr²h
V = 1/3(3.142)(25.56)²(30.77) = 21,053.98 cm³
Which figure will tessellate the plane? A. regular pentagon B. regular decagon C. regular octagon D. regular hexagon
A hexagon is composed of 6 congruent equilateral triangles. Each equilateral triangle has interior angle of 60 degrees. Adding 6 such angles together gets you to 360 degrees. So we've done one full rotation and covered every bit of the plane surrounding a given point. Extend this out and you'll be able to cover the plane. A similar situation happens with rectangles as well (think of a grid, or think of tiles on the wall or floor)
In contrast, a regular pentagon has interior angle 108 degrees. This is not a factor of 360, so there is no way to place regular pentagons to have them line up and not be a gap or overlap. This is why regular pentagons do not tessellate the plane. The same can be aside about decagons and octagons as well.