SOLUTION: verify the given identy cos^2B-sin^2B=2cos^2B-a

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Question 17840: verify the given identy
cos^2B-sin^2B=2cos^2B-a
Answer by venugopalramana(3286) About Me  (Show Source):
You can put this solution on YOUR website!
cos^2B-sin^2B=2cos^2B-a...this is corrected by me as follows
[cos(B)]^2-[sin(B)]^2=2[cos(B)]^2-1
use the formula .[cos(B)]^2+[sin(B)]^2=1..or...[sin(B)]^2=1-[cos(B)]^2..putting this
L.H.S.=[cos(B)]^2-{1-[cos(B)]^2}=[cos(B)]^2-1+[cos(B)]^2=2[cos(B)]^2-1=R.H.S.