What is the area of a square if its diagonal is 6Cm?

The area of the square is 18 cm2



The area of a square is:

area = side2

By Pythagoras:

side2 + side2 = diagonal2
⇒ 2 side2 = diagonal2
⇒ side2 = diagonal2 ÷ 2
⇒ area = diagonal2 ÷ 2

diagonal = 6cm, so:

area = (6 cm)2 ÷ 2
⇒ area = 18 cm2