How do I know whether to add or minus in Pythagoras's theorem?
Firstly it has to be a right angled trinagle. Even if it is an irregukar shape, draw a line in to make it a right angled triangle. When you have your right angled triangle remember it is ALWAYS + if it is the hypotenuse (longest side) and - if it is not the hypotenuse.
NM
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