If a windshield wiper covers an area of approximately 160 square inches when it rotates at an angle of 84°, find the length of the wiper to the nearest tenth of an inch.

Question

If a windshield wiper covers an area of approximately 160 square inches when it rotates at an angle of 84°, find the length of the wiper to the nearest tenth of an inch.

 

The length of the wiper is approximately     inches. 

Answer 1

A = πr², for an entire circle. You want 84/360 of a circle.

160 = (84/360)πr²

685.714 ≈ πr²

218.270 ≈ r²

14.77 ≈ r