Question

In figure 2, O is the center of the circle and B is a point on the circle. In rectangle OABC, if OA-5 and OC -6, what is the area of the circle?

A) 11 pie
B) 25 pie
C) 36 pie
D) 61 pie

Answer 1

The formula of an area of a circle:

`A_O=\pi r^2`

Use the Pythagorean theorem to calculate a length of a radius.

`r^2=5^2+6^2\\\\r^2=25+36\\\\r^2=61\to r=√(61)`

The area of a circle:

`A_O=\pi\cdot(√(61))^2=61\pi`

Answer: D) 61π