# Math Help - diagonal

1. ## diagonal

What is the length of the diagonal of a square with area 40 cm^2

2. The area of a square is:
$A = s^2$

Using this you can find the length of the a side of a square. To find the length of the diagonal, think of it as the hypotenuse $c$ of a triangle with legs $s$. Then, using the Pythagorean Theorem:
$s^2 + s^2 = c^2$