explain how

Asked by kumarijyoti jyoti | 7th Dec, 2012, 06:52: PM

Expert Answer:

We know the formula of cos2A.
cos2A = cos2A - sin2A
Put 2A = x , then A = x/2
We get
cos x= cos2x/2 - sin2x/2

Answered by  | 9th Dec, 2012, 11:32: AM

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