Answer: D) This triangle is a right triangle: 60^2+144^2 - 156^2 = 0
This is the same as saying 60^2 + 144^2 = 156^2
You would use the pythagorean theorem. In this case, a = 60, b = 144 and c = 156. The longest side is always the value of c. The order for the values of 'a' and 'b' do not matter. Convention usually has 'a' being the smaller of the two.