August 15, 2017 (8/15/17) was Pythagorean Theorem Day (see I missed Pythagorean Theorem Day). I was not even aware that there was such a day until this year, but it brought to my attention some really ...

In this triangle \(a^2 = b^2 + c^2\) and angle \(A\) is a right angle. Pythagoras' theorem only works for right-angled triangles, so you can use it to test whether a triangle has a right angle or not.

Use Pythagoras’ theorem to show a triangle is right-angled or to find one side of a right-angled triangle when two sides are known. Make sure you are confident at substituting into and manipulating ...