# Forty-five Plus A

Pro Problems > Math > Algebra > Functions > Trigonometry > Sum and Difference of Angles > Sine## Forty-five Plus A

sin(45 + A) = . Calculate cos(2A).

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Problem by Mr. Twitchell

## Solution

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Click here to assign this problem to your students.## Similar Problems

### Sines and Pythagorean Triples

If sin A = and sin B = , and both A and B lie in the first quadrant, find the value of sin (A + B).

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