# Sine

Pro Problems > Math > Algebra > Functions > Trigonometry > Sum and Difference of Angles > Sine# Featured Pro Problems

Calculate the cos(2A), given information about angle A and a sum of angles equation

Solve a trig problem involving a sum of angles with pythagorean triple values

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Forty-five Plus A, Sines and Pythagorean Triples# Ask Professor Puzzler

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