Question

If a square has a side of length $4cm$, what is the length of the diagonal?

Answer 1

The diagonal of a square divides the square into two right-angled triangles. Now, here in the square ABCD with side length $4cm$, using Pythagoras theorem, we have

$AC=\sqrt{A{B}^2+B{C}^2}=\sqrt{4^2+4^2}=\sqrt{32}=4\sqrt{2}cm$