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This essential trains for: SAT-I, SAT-II, GMAT, AMC-8.

A right angle triangle is obtained by cutting a rectangle in two congruent triangular halves:

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Elements of a right angle triangle:

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The square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the two legs.

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The reciprocal of the Pythagorean theorem is true: if three lengths satisfy the Pythagorean theorem, then the triangle with such lengths of sides is a right angle triangle.

If the equation is satisfied by a set of integer numbers, they are said to be 'Pythagorean triples'.

It is useful to memorize a few such triples:

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