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# Pythagoras Theorem The Pythagoras Theorem allows us to find the length of the third side on a right angle triangle if we know the other two lengths. Don’t forget: It only works on right angled triangles. You need to know at least two other lengths. The formal definition is: In a right angled triangle the sum of the square of the hypotenuse is equal to the sum of the squares of the other two sides. Algebraically a2 + b2 = c2 ('a' squared plus 'b' squared equals 'c' squared) c is always the hypotenuse. Therefore 32 + 42 = 52 (three squared plus four squared equals five squared) Which goes to 9 + 16 = 25 This can be used to find the length of an unknown side
a2 + b2 = c2 52 + 122 = c2 25 + 144 = 169 c2 = 169 c = √169 (square root of 169) c = 13 |
Check that you understand what these words mean in this document Right angled triangle: the geometrical shape of three sides whose one angle is 90 degrees. Hypotenuse: the side opposite the right angle. For further information visit: Proof of Pythagoras Theorem