7.
The area of this parallelogram is 120 ft. Find the value of h.
1
20 ft
12 ft
3 ft
15 ft
6 ft
Answer:
h = 6 ft.Step-by-step explanation:
area = base x height
where base = 20 ft.
height = ?
area = 120 ft²
plugin values into the formula
120 = 20 x height
height = 120
20
height = 6 ft.
what is 1.8÷0.004? using long division
Answer:
Hi! Answer will be below.
Step-by-step explanation:
The answer is 450.
If you divide 1.8 and 0.004 the answer you should get is 450.
Below I attached a picture of how to do long division...the picture is an example.
Hope this helps!:)
⭐️Have a wonderful day!⭐️
For the functions f(x)=4x−3 and g(x)=3x2+4x, find (f∘g)(x) and (g∘f)(x).
Answer:
(16x + 21) and (16x - 6)
Step-by-step explanation:
f(g(x)) = f(6 + 4x)
Applying the f(x) function on (6 + 4x) gives
4(6 + 4x) - 3
Which equals 16x + 24 - 3
= 16x + 21
g(f(x)) = g(4x - 3)
Applying the g(x) function on (4x - 3) gives
6 + 4(4x - 3)
Which equals 6 + 16x - 12
= 16x - 6
Answer:
(g∘f)(x)=48x2+48x+10
(g∘f)(x)=12x^2-6
Step-by-step explanation:
To find (f∘g)(x), use the definition of (f∘g)(x),
(f∘g)(x)=f(g(x))
Substituting 3x2−2 for g(x) gives
(f∘g)(x)=f(3x2−2)
Find f(3x2−2), where f(x)=4x+2, and simplify to get
(f∘g)(x)(f∘g)(x)(f∘g)(x)=4(3x2−2)+2=12x2−8+2=12x2−6
To find (g∘f)(x), use the definition of (g∘f)(x),
(g∘f)(x)=g(f(x))
Substituting 4x+2 for f(x) gives
(g∘f)(x)=g(4x+2)
Find g(4x+2), where g(x)=3x2−2, and simplify to get
(g∘f)(x)=3(4x+2)^2−2
(g∘f)(x)=48x2+48x+12−2
(g∘f)(x)=48x2+48x+10
What is 3/4 improper or proper or mixed
Answer:
proper because the numerator is lower than the denominator
What is the inequality
Answer:
x ≥ 4
Step-by-step explanation:
Well to find the inequality we need to single out x,
4x - 1 ≥ 15
+1 to both sides
4x ≥ 16
Divide 4 by both sides
x ≥ 4
Thus,
x is greater than or equal to 4.
Hope this helps :)
What will happen to the median height of the outlier is removed?
{75, 63, 58, 59, 63, 62, 56, 59)
Answer:
The meadian decreases by 1.5 when the outlier is removed.
Step-by-step explanation:
Well first we need to find the median of the following data set,
(75, 63, 58, 59, 63, 62, 56, 59)
So we order the set from least to greatest,
56, 58, 59, 59, 62, 63, 63, 75
Then we cross all the side numbers,
Which gets us 59 and 62.
59 + 62 = 121.
121 / 2 = 60.5
So 65 is the median before the outlier is removed.
Now when we remove the outlier which is 75.
Then we order it again,
56, 58, 59, 59, 62, 63, 63
Which gets us 59 as the median.
Thus,
the median height decreases by 1.5 units when the outlier is removed.
Hope this helps :)
The price of a boat that Arthur wants is $29,450. Arthur finances this by paying $6000 down and monthly payment of $792.22 for 36 months.
a. Determine the amount to be financed.15a. _______________
b. Determine the installment price.b. _________________
c. Determine the finance charge.c. _________________
Answer:
see details below
Step-by-step explanation:
The price of a boat that Arthur wants is $29,450. Arthur finances this by paying $6000 down and monthly payment of $792.22 for 36 months.
a. Determine the amount to be financed.15a. ___$23450____________
29450 - 6000 = 23450
b. Determine the installment price.b. ___$792,22______________
"monthly payment of $792.22"
c. Determine the finance charge.c. __$5069.92_______________
A = 792.22
n = 36
finance charge = total paid - amount to be financed
= 36*792.22 - 23450
= 5069.92
Find the value of n such that 540n is perfect cube.
Answer:
1.35
Step-by-step explanation:
next cube above 540 is 729
to get to 729: 729 / 540 = 1.35
n = 1.35
Over the last three evenings, Melissa received a total of 126 phone calls at the call center. The first evening, she received 6 more calls than the third evening. The second evening, she received 4 times as many calls as the third evening. How many phone calls did she receive each evening? Number of phone calls the first evening: Number of phone calls the second evening: Number of phone calls the third evening:
Answer:
calls first evening = 26
calls second evening = 80
calls third evening = 20
Step-by-step explanation:
Let x = calls third evening
x+6 = calls first evening
4x = calls second evening
x+6 + 4x + x = total calls = 126
Combine like terms
6x+6 = 126
Subtract 6 from each side
6x =120
Divide by 6
6x/6 =120/6
x = 20
x+6 = calls first evening = 20+6 = 26
4x = calls second evening = 4*20 = 80
Let x = calls third evening = 20
select the fraction equivalent of 0.06. reduce to the lowest terms
Answer: 3/50
Step-by-step explanation:
0.06 = 6/100 , 100 would be the denominator because we have two figures after the decimal point. Each figures can also be represented by 10,
Again,
0.06 = 6 × 10-²
Now 0.06 = 6/100
= 3/50.
Therefore, the fractional form = 3/50 in its lowest term.
.If you add 5 to both the numerator and the denominator of a fraction, you obtain 2/3; however, if '
you subtract 5 from both the numerator and the denominator of the same fraction, you obtain 1/4. For what fraction is this true?
Answer:
The fraction that this is true for = 7/13
Step-by-step explanation:
From the above question
Let the numerator be represented by a
Let the denominator be represented by b
If you add 5 to both the numerator and the denominator of a fraction, you obtain 2/3
This means:
a + 5/b + 5 = 2/3
Cross Multiply
3(a + 5) = 2(b + 5)
3a + 15 = 2b + 10
Collect like terms
3a - 2b = 10 - 15
3a - 2b = -5..........Equation 1
If you subtract 5 from both the numerator and the denominator of the same fraction, you obtain 1/4
This means:
a - 5/b - 5 = 1/4
Cross Multiply
4(a - 5) = 1(b - 5)
4a - 20 = b - 5
Collect like terms
4a - b = 20 - 5
4a - b = 15..........Equation 2
b = 4a - 15
3a - 2b = -5..........Equation 1
4a - b = 15..........Equation 2
Substitute 4a - 15 for b in equation 1
3a - 2b = -5..........Equation 1
3a - 2(4a - 15) = -5
3a - 8a + 30 = -5
Collect like terms
3a - 8a = -5 - 30
-5a = -35
a = -35/-5
a = 7
Therefore, the numerator of the fraction = 7
Substitute 7 for a in Equation 2
4a - b = 15..........Equation 2
4 × 7 - b = 15
28 - b =15
28 - 15 = b
b = 13
The denominator = b is 13.
Therefore,the fraction which this is true for = 7/13
To confirm
a) If you add 5 to both the numerator and the denominator of a fraction, you obtain 2/3
This means:
a + 5/b + 5 = 2/3
7 + 5/ 13 + 5 = 2/3
12/18 = 2/3
Divide numerator and denominator by of the left hand side by 6
12÷ 6/ 18 ÷ 6 = 2/3
2/3 =2/3
If you subtract 5 from both the numerator and the denominator of the same fraction, you obtain 1/4
This means:
a - 5/b - 5 = 1/4
7 - 5/13 - 5 = 1/4
2/8 = 1/4
Divide the numerator and denominator of the left hand side by 2
2÷2/8 ÷ 2 = 1/4
1/4 = 1/4
From the above confirmation, the fraction that this is true for is 7/13
determining the probability of events. please help :)
Answer:
C. 1/8
Step-by-step explanation:
Probability of shooting a goal on a throw is 2/4 = 1/2.
Probability of 3 in a row is (1/2)³ = 1/8.
Which equation represents a population of 250 animals that decreases at an annual rate of 21%
Answer:
y= 250( 1-0.21)^x
Step-by-step explanation:
This represents exponential decay
The equation represents a population of 250 animals that decreases at an annual rate of 21% will be p = 250(0.79)[tex].^t[/tex] The correct option is C.
What is an exponential function?The mathematical expression f(x)=[tex]e^t[/tex] denotes the exponential function. The term typically refers to the positive-valued function of a real variable, unless otherwise specified.
Expression in maths is defined as the collection of the numbers variables and functions by using signs like addition, subtraction, multiplication, and division.
It is given that a population of 250 animals is decreasing at an annual rate of 21%.
p = a x b[tex].^t[/tex]
p = a x (1+r)[tex].^t[/tex]
p = 250 x (1+(-0.21))[tex].^t[/tex]
p = 250(0.79)[tex].^t[/tex]
Note that r = -0.21 is negative to indicate we have exponential decay.
Hence, the equation represents a population of 250 animals that decreases at an annual rate of 21% will be p = 250(0.79)[tex].^t[/tex] The correct option is C.
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What is the radius of a circle given by the equation x2 + y2 – 2x + 8y – 47= 0? radius = units
Answer:
8 units
Step-by-step explanation:
We need to rewrite an equation in the standard for a circle form.
r is radius.
(x−h)²+(y−k)²= r²
x² + y² – 2x + 8y – 47= 0
x² - 2x + y² + 8y - 47 = 0
x² - 2*x *1+ 1 ²- 1² + y² + 2*4*y + 4² - 4² - 47 = 0
(x - 1)² + (y + 4)² - 1 - 16 -47 =0
(x - 1)² + (y + 4)² - 64=0
(x - 1)² + (y + 4)² = 8²
Radius is 8.
The radius of the circle is 8 units
What is radius?The radius of a circle is a line drawn from the center to the circumference of the circle
The equation of the circle is given as;
[tex]x^2 + y^2 - 2x + 8y - 47 = 0[/tex]
Rewrite the equation as:
[tex]x^2 - 2x + y^2 + 8y = 47[/tex]
Next, we rewrite the equation in the standard form
So, we have:
x^2 - 2x + 1^2 - 1^2 + y^2 + 8y + 4^2 - 4^2 = 47
Evaluate the exponents
x^2 - 2x + 1 - 1 + y^2 + 8y + 16 - 16 = 47
Rewrite the equation as follows:
x^2 - 2x + 1 + y^2 + 8y + 16 = 47 + 1 + 16
Express as perfect squares
(x - 1)² + (y + 4)² = 64
(x - 1)² + (y + 4)² = 8^2
The radius of the circle is calculated as:
r^2 = 8^2
By comparison, we have:
r = 8
Hence, the radius of the circle is 8 units
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3^x = 27^a+b and a^2-b^2/(a-b)=5 What is x?
A father is 60 years old and his son is half his age. How old was the boy when his father was four times his age?
Hey there! I'm happy to help!
We see that the father is 60 years old, and the son is half of that age, so this means that the son is 30 years old.
We want to see the age the son was at when the father was four times his age. We know that the father is thirty years older than him, so we can write this equation with s representing the age of the son.
s+30=4s (30 years older than the son is equal to to four times the son's age at the time)
We subtract 30 from both sides.
s=4s-30
We subtract 4s from both sides.
-3s=-30
We divide both sides by -3.
s=10
Therefore, the boy was 10 when his father was four times his age. This is because his father would have been 40 because that is 30 more years than 10, and it is four times ten!
Have a wonderful day! :D
Need answers ASAP!!!!! (due today)
Answer:
15) 2.08m
Step-by-step explanation:
We kow tanA= p/b
Here, A=33°
b=3.2m
Then,
tan33°=p/3.2
0.65=p/3.2
p=0.65*3.2
p=2.08
So, The height of tree is 2.08m
14) 59.58ft
tan50°=p/b
1.19=p/50
p=59.58ft
So, The height of signpost is 59.58ft
In both of these problems, we will be using trigonometry! Remember, SOH-CAH-TOA.
14. x = 13.5950 ft
Visualization of the problem is attached below.
We want to find out the opposite side to the angle, and we know the adjacent side. Therefore, we should use the tangent function.
tan(50) = x / 50
x = tan(50) * 50
x = 13.5950 ft (round off wherever you need)
15. x = 241.0016 m
The visualization of the problem is already given. We know the same information as we need in the previous problems, an angle and an adjacent side, and we want to find the opposite side. Therefore, we should use the tangent function.
tan(33) = x / 3.2
x = tan(33) * 3.2
x = 241.0016 (round off wherever you need)
Hope this helps!! :)
by what number 7whole 2/3be divided to get 4whole1/3
Answer: 1 30/39
Step-by-step explanation:
Because y/x=z and y/z=x are true with the same values, simply do 7 2/3 divided by 4 1/3 to get 69/39.
Hope it helps <3
A simple random sample of 20 third-grade children from a certain school district is selected, and each is given a test to measure his/her reading ability. You are interested in calculating a 95% confidence interval for the population mean score. In the sample, the mean score is 64 points, and the standard deviation is 12 points. What is the margin of error associated with the confidence interval
Answer:
Margin of Error = ME =± 5.2592
Step-by-step explanation:
In the given question n= 20 < 30
Then according to the central limit theorem z test will be applied in which the standard error will be σ/√n.
Sample Mean = μ = 64
Standard Deviation= S= σ = 12
Confidence Interval = 95 %
α= 0.05
Critical Value for two tailed test for ∝= 0.05 = ±1.96
Margin of Error = ME = Standard Error *Critical Value
ME = 12/√20( ±1.96)=
ME = 2.6833*( ±1.96)= ± 5.2592
The standard error for this test is σ/√n
=12/√20
=2.6833
Question 8(Multiple Choice Worth 1 points) (07.01 MC) Find the measure of arc DF. Circle A with chords EF and CD that intersect at point G, the measure of arc EC is 5x plus 10 degrees, the measure of angle EGC is 70 degrees, and the measure of arc DF is 11x plus 2 degrees. 50° 90° 100° 140°
Answer: 90°
Step-by-step explanation:
As known ∡EGC=(arcEC+arcDF)/2
arcEC+arcDF=70°*2
5x+10+11x+2=140
16x+12=140
16x=128
x=128:16
x=8
So arcDF=11*x+2=11*8+2=90°
The measure of arc DF is 90°.
What is circle?A circle is a closed, two-dimensional object where every point in the plane is equally spaced from a central point. The line of reflection symmetry is formed by all lines that traverse the circle. Additionally, every angle has rotational symmetry around the centre.
Given, Circle A with chords EF and CD that intersect at point G,
arc EC = 5x + 10°
arc DF = 11x + 2°
∠EGC = 70°
The measure of the inner angle is the semi-sum of the arcs comprising it and its opposite
so
∠EGC=(1/2)[arc EC+arc DF]
substitute the values
70 = 1/2(5x + 10 + 11x + 2)
70 = 1/2(16x + 12)
140 = 16x + 12
16x = 128
x = 128/16 = 8
so ac DF = 11x + 2
arc DF = 11(8) + 2
arc DF= 88 + 2 = 90°
Hence the value of arc DF is 90°.
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What are the dimensions of the rectangle? PLEASE HELP!!
Answer:
2(x^2 + 8x -55)
Step-by-step explanation:
Well to do the box method we first need to simplify the given equation further to,
[tex]2x^2 + 16x - 110\\[/tex],
For this quadratic the box method doesn't work so we can divide everything by 2 make make it
2(x^2 + 8x -55)
Thus,
[tex]2x^2 + 16x - 110\\[/tex] factored is 2(x^2 + 8x -55).
Hope this helps :)
In a study of the accuracy of fast food drive-through orders, Restaurant A had 302accurate orders and 59that were not accurate.a. Construct a 95%confidence interval estimate of the percentage of orders that are not accurate.b. Compare the results from part (a) to this 95%confidence interval for the percentage of orders that are not accurate at Restaurant B: 0.143less thanpless than0.219.What do you conclude?
Answer:
(a) A 95% confidence interval estimate of the percentage of orders that are not accurate is [0.125, 0.201].
(b) We can conclude that both restaurants can have the same inaccuracy rate due to the overlap of interval areas.
Step-by-step explanation:
We are given that in a study of the accuracy of fast food drive-through orders, Restaurant A had 302 accurate orders and 59 orders that were not accurate.
Firstly, the pivotal quantity for finding the confidence interval for the population proportion is given by;
P.Q. = [tex]\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] ~ N(0,1)
where, [tex]\hat p[/tex] = sample proportion of orders that were not accurate = [tex]\frac{59}{361}[/tex] = 0.163
n = sample of total orders = 302 + 59 = 361
p = population proportion of orders that are not accurate
Here for constructing a 95% confidence interval we have used a One-sample z-test for proportions.
So, 95% confidence interval for the population proportion, p is ;
P(-1.96 < N(0,1) < 1.96) = 0.95 {As the critical value of z at 2.5% level
of significance are -1.96 & 1.96}
P(-1.96 < [tex]\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] < 1.96) = 0.95
P( [tex]-1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] < [tex]{\hat p-p}[/tex] < [tex]1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] ) = 0.95
P( [tex]\hat p-1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] < p < [tex]\hat p+1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] ) = 0.95
95% confidence interval for p = [ [tex]\hat p-1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] , [tex]\hat p+1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] ]
= [ [tex]0.163 -1.96 \times {\sqrt{\frac{0.163(1-0.163)}{361} } }[/tex] , [tex]0.163 +1.96 \times {\sqrt{\frac{0.163(1-0.163)}{361} } }[/tex] ]
= [0.125, 0.201]
(a) Therefore, a 95% confidence interval estimate of the percentage of orders that are not accurate is [0.125, 0.201].
(b) We are given that the 95% confidence interval for the percentage of orders that are not accurate at Restaurant B is [0.143 < p < 0.219].
Here we can observe that there is a common area of inaccurate order of 0.058 or 5.85% for both the restaurants.
So, we can conclude that both restaurants can have the same inaccuracy rate due to the overlap of interval areas.
Which graph best models the inequality y<_ -2/5x+2
Answer:
Step-by-step explanation:
Simplify each term.
y ≤ −2x/5 + 2
Find the slope and the y-intercept for the boundary line.
Slope: -2/5
Y-intercept: 2
Graph a solid line, then shade the area below the boundary line since
y is less than -2x/5 + 2
y ≤ −2x/5 + 2
Hope this can help
A= 63°
C = 7.75 inch
B = 47°
Oblique Triangle
4. Refer to the oblique triangle shown. What's the size of angle C?
O A. 60°
B. 125°
O C. 45°
O D. 70°
Answer:
Option D is correct.
Angle C = 70°
Step-by-step explanation:
The sum of angles in a triangle = 180°
So,
(Angle A) + (Angle B) + (Angle C) = 180°
(Angle A) = 67°
(Angle B) = 43°
(Angle C) = ?
67° + 43° + (Angle C) = 180°
Angle C = 180 - 67 - 43 = 70°
Angle C = 70°
Hope this Helps!!!
Probability of landing on even # on a spinner; probability of rolling an odd # on a die
Answer:
Spinner: 50%
Die: 50%
Step-by-step explanation:
Well for the spinner it depends on the amount of numbers it has,
in this case we’ll use 6.
So The probability of landing on the even numbers in a 6 numbered spinner.
2, 4, 6
3/6
50%
Your average die has 6 sides so the odd numbers are,
1, 3, 5
3/6
50%
In a random sample of 400 residents of Boston, 320 residents indicated that they voted for Obama in the last presidential election. Develop a 95% confidence interval estimate for the proportion of all Boston residents who voted for Obama.
Answer:
C.I = 0.7608 ≤ p ≤ 0.8392
Step-by-step explanation:
Given that:
Let consider a random sample n = 400 candidates where 320 residents indicated that they voted for Obama
probability [tex]\hat p = \dfrac{320}{400}[/tex]
= 0.8
Level of significance ∝ = 100 -95%
= 5%
= 0.05
The objective is to develop a 95% confidence interval estimate for the proportion of all Boston residents who voted for Obama.
The confidence internal can be computed as:
[tex]=\hat p \pm Z_{\alpha/2} \sqrt{\dfrac{ p(1-p)}{n } }[/tex]
where;
[tex]Z_{0.05/2}[/tex] = [tex]Z_{0.025}[/tex] = 1.960
SO;
[tex]=0.8 \pm 1.960 \sqrt{\dfrac{ 0.8(1-0.8)}{400 } }[/tex]
[tex]=0.8 \pm 1.960 \sqrt{\dfrac{ 0.8(0.2)}{400 } }[/tex]
[tex]=0.8 \pm 1.960 \sqrt{\dfrac{ 0.16}{400 } }[/tex]
[tex]=0.8 \pm 1.960 \sqrt{4 \times 10^{-4}}[/tex]
[tex]=0.8 \pm 1.960 \times 0.02}[/tex]
[tex]=0.8 \pm 0.0392[/tex]
= 0.8 - 0.0392 OR 0.8 + 0.0392
= 0.7608 OR 0.8392
Thus; C.I = 0.7608 ≤ p ≤ 0.8392
A 24-centimeter by 119-centimeter piece of cardboard is used to make an open-top box by removing a square from each corner of the cardboard and folding up the flaps on each side. What size square should be cut from each corner to get a box with the maximum volume
Answer:
The size square removed from each corner = 32.15 cm²
Step-by-step explanation:
The volume of the box = Length * Breadth * Height
Let r be the size removed from each corner
Note that at maximum volume, [tex]\frac{dV}{dr} = 0[/tex]
The original length of the cardboard is 119 cm, if you remove a size of r (This typically will be the height of the box) from the corner, since there are two corners corresponding to the length of the box, the length of the box will be:
Length, L = 119 - 2r
Similarly for the breadth, B = 24 - 2r
And the height as stated earlier, H = r
Volume, V = L*B*H
V = (119-2r)(24-2r)r
V = r(2856 - 238r - 48r + 4r²)
V = 4r³ - 286r² + 2856r
At maximum volume dV/dr = 0
dV/dr = 12r² - 572r + 2856
12r² - 572r + 2856 = 0
By solving the quadratic equation above for the value of r:
r = 5.67 or 42
r cannot be 42 because the size removed from the corner of the cardboard cannot be more than the width of the cardboard.
Note that the area of a square is r²
Therefore, the size square removed from each corner = 5.67² = 32.15 cm²
What is the measure of JOK, given that GH=JK ?
A.
288
B.
108
C.
72
D.
18
Answer:
72 degrees.
Step-by-step explanation:
The angle marked as 72 degrees and the angle of JOK are considered vertically opposite angles in relation to each other. This relationship means that the angles are equal.
Answer:
[tex]\boxed{Option \ C}[/tex]
Step-by-step explanation:
Congruent arcs subtend congruent central angles.
So,
∠GOH ≅ ∠JOK
∠JOK = 72 degrees
A sample of 4 different calculators is randomly selected from a group containing 42 that are defective and 20 that have no defects. What is the probability that all four of the calculators selected are defective? No replacement. Round to four decimal places.
Answer: = approx 0.2006
Step-by-step explanation:
The probability that first 1 randomly selected calculator is defective is
P(1st defect)= 42/(42+20)=42/62=21/31
If the first calculator is defective the residual number of defective calculators is 42-1=41. The residual total number number of calculators is 62-1=61
So the probability that second calculator is defected
P(2nd defective)=41/61
If both previous calculators are defective the residual number of defective calculators is 42-2=40. Total residual number of calculators is 62-2=60
So the probability that third calculator is defected
P(3rd defective)=40/60=2/3
Finally the probability that also fourth calculator is defective is 39/59
P(4th defective)=39/59
The resulted probability that all 4 calculators are defective is
P(all 4 are defective)= P(1st defect)* P(2nd defect) * P(3rd defect)* P(4th defect)=21*41*2*39/(31*61*3*59)=67158/334707=0.200647... = approx 0.2006
M angle D=? What is the degree of the angle?
Answer:
80°Step-by-step explanation:
In ACB and ECD
AC =~ CE [ Given ]
BC =~ CD [ Given ]
<ACD =~ <ECD [ Vertical angles ]
Hence, ∆ ACB =~ ECD by SAS congruency of triangles.
Then, <B = <D
In ∆ABC , sum of all three angles must be 180°
<A + <B + <C = 180°
plug the values
[tex] 30 + < d \: + 70 = 180[/tex]
Add the numbers
[tex]100 + < d = 180[/tex]
Move constant to R.H.S and change it's sign
[tex] < d = 180 - 110[/tex]
Subtract the numbers
[tex] < d = 80[/tex] °
Hope this helps..
Best regards!!