The area of a rectangular piece of plastic is 80 square millimeters. The perimeter is 36 millimeters. What are the dimensions of the piece of plastic

Question

The area of a rectangular piece of plastic is 80 square millimeters. The perimeter is 36 millimeters. What are the dimensions of the piece of plastic

Answer 1

A = lw

80 = lw

80/w = l

P = 2l + 2w

36 = 2(80/w) + 2w

36 = 160/w + 2w

Multiply both sides by w.

36w = 160 + 2w²

2w² - 36w + 160 = 0

Divide by 2.

w² - 18w + 80 = 0

(w - 10)(w - 8) = 0

w = 10 mm or w = 8 mm

l = 8 mm or l = 10 mm