Question

Each diagonal of a square is 12cm long.find its area.

Answer 1

Diagonal = √2side of square
let side be = a
12 = √2a ( Diagonal = √2 side)
12/√2 cm = a
Perimeter = 4 x side 
= 4 x a
= 4 x 12/√2
= 48/√2
= 48√2/2. (multiplying numerator and denominator by √2)
= 24√2
Area = Side x Side 
= 12/√2 x 12/√2
= 144/2
= 72 cm sq.