The Pythagorean Theorem

Mathematics — Second Preparatory

Common mistakes

Applying the theorem to a triangle that is not right-angled. For example, the triangle with sides 5, 6 and 7 is not right-angled, because 5² + 6² = 61 and 7² = 49.
Putting the hypotenuse in the wrong place in the formula. The hypotenuse is always the side opposite the right angle, and it is the longest.
Forgetting the square root at the end when finding a length.
Confusing the relation with a sum. The correct relation is a² + b² = c², not a + b = c.

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