 Pythagoras' theorem

 
Pythagoras' theorem is an extremely important geometric law, which is used in the derivation of many other geometrical solutions. It does not in itself give angles, which may be determined with trigonometry. The area of the triangle may be determined from the two short sides using the formula area=(1/2)*[side a]*[side b] (a special case of area=(1/2)*base*height, which is general for any triangle). Remember that you only need to fill in two sides, and the third will be calculated.  