Question

The length of a rectangle is 3 cm longer than its width.

If the perimeter of the rectangle is 42 cm, find its area.

Answer 1

108 cm²

Explanation:

Area of a rectangle, A = length, l × width, w

Perimeter of a rectangle = (2 × length) + (2 × width)

42 cm = 2l + 2w

but length = w + 3cm

42 cm = 2(w + 3cm) + 2w

42 cm = 2w + 6cm + 2w

42 cm = 6cm + 4w

4w = (42 - 6) cm

4w = 36 cm

》w = 9cm

》l = w + 3cm = 9cm + 3cm

l = 12 cm

Area = 12 × 9 = 108 cm²