Answer:
Step-by-step explanation: I think it's D
Sum of angles of regular polygon = 180*(n-2), n - number of sides, or angles.
120n=180*(n-2)
120n=180n-360
180n-120n=360
60n =360
n=6
It is hexagon.
Using proportions, the lengths of the unknown sides are given as follows:
<h3>What is a proportion?</h3>
A proportion is a fraction of a total amount, and the measures are related using a rule of three.
In this problem, the triangles are similar, hence the lengths of it's sides follow the proportion given next:

Applying cross multiplication:
2x(x - 3) = 20
2x² - 6x - 20 = 0
x² - 3x - 10 = 0
(x - 5)(x + 2) = 0.
Then the positive solution is:
x - 5 = 0 -> x = 5.
And the lenghts are:
More can be learned about proportions at brainly.com/question/24372153
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Answer:

Step-by-step explanation:
sine of A = 
opposite = 5
adjacent = 12
hypotenuse = 13
Answer:
38
Step-by-step explanation:
since angle 6 is opposite of the angle 38, they both are same angle