Answer:
The answer to your question is letter A.
Step-by-step explanation:
Cosine is the trigonometric function that the adjacent side and the hypotenuse.
Formula
cos x =
For x:
Adjacent side = 5
Hypotenuse = 13
Substitution
r = 5 cm
A = πr²
78.53 = (3.14)r²
divide by 3.14
25 = r²
r = ±5
r = 5