Identity a and P in the following expression which is the ri

Identity a and P in the following expression which is the right side of the formula for cos (alpha - beta) cos(175 degree)cos(55 degree) + sin(175 degree)sin(55 degree) A. alpha = 175 degree, beta = 55 degree B. alpha = -55 degree, beta = 175 degree C. alpha = 55 degree, beta = -175 degree D. alpha = -175 degree. beta = 55 degree

Solution

cos ( alpha - beta ) = cos(alpha) cos (beta) + sin(alpha) sin (beta) -------> (1 )

given

cos ( alpha - beta ) = cos(175) cos (55) + sin(175) sin (55) ------> ( 2 )

compare ( 1 ) and ( 2 )

then

alpha = 175 and beta = 55