Question

A metal washer is made by cutting out a circle 13.2 mm in diameter from a larger circle. To the nearest tenth, what is the area of the washer?
547.1 mm2

60.8 mm2

972.6 mm2

243.3 mm2

Answer 1

The area of the washer will be the area of the smaller circle SUBTRACTED from the area of the larger circle.

Area of a circle = pi * r^2 where r is your radius (which is half the diameter).
Larger circle area = pi *(diameter/2) ^2.
Smaller circle area = pi * (13.2/2)^2 = pi * 6.6^2 = 136.8484....

So...the area of the washer = larger circle area - 136.4848...