Question

The perimeter of a rectangle is 42cm and its diagonal is 15cm. Find the dimension of the rectangle

Answer 1

p=2*(L+l)=42
L+l=42:2
L+l=21
(L+l)^2=441
use the formula (a+b)^2=a^2+b^2+2ab
(L^2+l^2)+2l*L=441

D= V L^2+l^2= 15
L^2+l^2=225

225+2l*L=441

2l*L=441-225=216
l*L=216:2
A=108