Question

Arc AB of circle O contgains 72 degree and is 6 pi long. Find area of circle O.

a. 9
b. 36
c. 30 pi
d. 225 pi
e. 900

please answer and explain

Answer 1

72 is 1/5 of 360, a full circle.
So, 5 * 6pi = 30pi and is the full circumference

since c = 2pi r, r = 15
since a = pi r^2, a = 225 pi

Answer 2

c = 2 pi r
30 = 2 pi r
r=15

a= pi r^2
= pi 25^2
= 225 pi

thank you