SOLUTION: What is the double angle formula derived from the sine and cosine subtraction formulas?
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Question 194692: What is the double angle formula derived from the sine and cosine subtraction formulas?
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
Sum and difference formulae:
 = \sin{\alpha}\cos{\beta}\pm\cos{\alpha}\sin{\beta})
 = \cos{\alpha}\cos{\beta}\mp\sin{\alpha}\sin{\beta})
So:
 = \sin{\alpha}\cos{\alpha}+\cos{\alpha}\sin{\alpha} = 2\sin{\alpha}\cos{\alpha})
And:
 = \cos{\alpha}\cos{\alpha}-\sin{\alpha}\sin{\alpha} = \cos^2{\alpha} - \sin^2{\alpha})
John
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