Question

A circle is drawn on the coordinate plane. It has a center at (2, 1) and passes through the point (2, 5). What is the approximate circumference of the circle?

Answer 1

First we need to find the radius.  Using Pythagorean theorem we can find the radius which is the distance between the center and any point along the circle:

r=((5-1)^2+(2-2)^2)^(1/2)

r=(4^2-0^2)^(1/2)

r=4 units.

Circumference=2pr so our circumference is 8p units^2

Approximately 25.13 u^2