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# Compound angle or R,A formula watch

1. Hey again guys,

I need to solve sin(x+30) = 2cos(x+45)

I'm thinking that to simplify this, I should use compound angle formula on the sin function and the cos function. Is this the right way to go about solving it, or should I be using R,A formula. And why?

Thanks
2. You can use either or because both can independently be derived from the other.

Given that, I would use compound angle because I find evaluating sine and cosine (even if it's both) easier than evaluating tangent, and you don't have to go around finding the coefficients a and b.

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Updated: March 16, 2013
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