Question

A motion detector at the corner of a building can detect motion outside within a radius of 20 feet. Within what area can it detect motion? The building takes up ¼ of the circle

Answer 1

To find area of full circle

A= pi*r^2
A=pi*20^2
A=1256 ft^2

Now figure only for the 3/4 of circle the building don’t cover

A=1256*.75
A=942 ft^2

So the area it can detect is 942 ft^2