Question

The length and breadth of a rectangle are in the ratio 4 : 3. If the diagonal measures 25 cm, then the perimeter of the rectangle is

(a) 56 cm (b) 60 cm

(c) 70 cm (d) 80 cm

Answer 1

Let l = 4x, b = 3x, Then $(diagonal{)}^2=l^2+b^2$

$\Rightarrow (25{)}^2=16x^2+9x^2$

$\Rightarrow 25x^2=625$

$\Rightarrow x^2=25\Rightarrow x=5$

$\Rightarrow l=4x=4\times 5=20cm$

$b=3x=3\times 5=15cm$

Perimeter = 2(l+b) = 2 (20+15)

=$2\times 35=70cm$