Question

Work out the area of a rectangle with base, b = 20mm and perimeter, P = 42mm.

Answer 1

20mm

Explanation:

base=20mm

base x 2 because there are two long lines

20 x 2 = 40

42-40=2

amount needed on either side to balance

height=1mm

20 x 1 = 20mm

area = 20mm

Answer 2

Let the length of the rectangle be 'l'

We have,

Perimeter of rectangle, P = 42mm.

`or, 2(l+b) = 42\\or, l +b = (42)/(2) = 21\\or, l + 20 = 21\\or, l = 1mm\\`

Area of rectangle =
`lb = 1(20) = 20mm^(2)`