Question

The perimeter of a square is 20 cm. How do you find the length of a diagonal?

Answer 1

Let `a` be the side of the square .Its perimeter equals with `4a` hence `4a=20=>a=5cm` .Now the diagonal `d` is the hypotenese of the right triangle with sides those of the square so

`d^2=a^2+a^2=>d=sqrt2*a=>d=5*sqrt2`