# Sum of two squares

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Sum of two squares

In mathematics, sums of two squares occur in a number of contexts:

* The Pythagorean theorem says that the square on the hypotenuse of a right triangle is equal in area to the sum of the squares on the legs
* Brahmagupta–Fibonacci identity says the set of all sums of two squares is closed under multiplication.
* Fermat's theorem on sums of two squares says which integers are sums of two squares.
** A separate article discusses Proofs of Fermat's theorem on sums of two squares

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