Pythagoras' Theorem  
Summary 
the theorem of pythagoras is an equation connecting the longest side of a rightangled triangle (called the hypotenuse) with the other two sides. it can be used to find the length of one side of a rightangled triangle given the other two sides. it applies only to rightangled triangles. 
Key Skills 

Vocabulary 
pythagoras' theorem, right angle, hypotenuse, pythagorean triple. 