If sec (x + α) + sec(x - α) = 2 sec x, prove that cos x

Given: sec (x + α) + sec(x - α) = 2 sec x



sec (x + α) + sec(x - α) = 2 sec x








{∵ 2 cos A cos B = cos (A + B) + cos (A – B)}






{∵ cos 2x = 2 cos2 x – 1}




{∵ cos 2x = 2 cos2 x – 1}











Hence Proved


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