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Pythagorean theorem
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In a right triangle with legs a and b and hypotenuse c, one has

    a^2 + b^2 = c^2.

Given any two sides you can solve for the third:

    c = √(a^2 + b^2),
    a = √(c^2 − b^2),
    b = √(c^2 − a^2),

with the validity condition c ≥ max(a, b) and equality indicating
the degenerate (collinear) case.
