How to prove #cos(theta-pi/2)=sin(theta)# is false?

1 Answer
George C.
Feb 23, 2018

#cos(theta - pi/2) = sin(theta)# is true

Explanation:

By the difference of angles formula for #cos(alpha - beta)# we find:

#cos(theta - pi/2) = cos(theta) cos(pi/2) + sin(theta) sin(pi/2)#

#color(white)(cos(theta - pi/2)) = cos(theta)(0) + sin(theta)(1)#

#color(white)(cos(theta - pi/2)) = sin(theta)#

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