How do I use Pythagoras' Theorem to calculate the hypotenuse of a triangle?

[use of board] So, Pythagoras' theorem states that a^2+b^2=c^2. Therefore, we need to mark the triangle with a, b &c. a and b do not matter, c must be the longest edge, that creates the diagonal. Put the lengths a and b into the theorem. According to BIDMAS, you must square the numbers first, then add them together afterwards. This will give you a value for c^2. Use a calculator (or your brain) to find the square root of this number... This will leave you with c, the hypotenuse.