The Pythagorean Theorem also states that the sum of the squares of the lengths of the legs of a right triangle is equal to the square of the length of the hypotenuse.
In other words, for the triangle shown below, a² + b² = c².
In the image below, I have drawn a triangle on my whiteboard.
In the triangle that is shown below, the legs, <em>a </em>and <em>b, </em>are the perpendicular sides of the right triangle and the hypotenuse, <em>c</em>, is the side opposite the right angle.
This only applies to right triangles!
You can use this theorem to find out if a triangle is an acute triangle, a right triangle, or even an obtuse triangle.