Question

The perimeter of a rectangular board is 70 cm. Taking its length as x cm, find its width in terms of x.
If the area of the rectangular board is 300 cm²; find its dimensions.

Answer 1

Let b be the breadth of the rectangle. then its perimeter

2(x + b) = 70

x + b = 35

b = 35 - x

Again

x × b = 300

x(35 - x) = 300

35x - x² = 300

0 = x² - 35x + 300

(x - 15) (x - 20) = 0

x = 15, 20

Hence, its length is 20 cm and width is 15 cm.