How this equation is equal to this equation?

C Calado99 New member Joined Jan 10, 2021 Messages 8 Jul 18, 2021 #1 How this equation is equal to this equation?

Jomo Elite Member Joined Dec 30, 2014 Messages 10,718 Jul 18, 2021 #2 pi + pi/6 = pi(1+ 1/6) = pi(7/6) = 7pi/6 cos(-u) = cos(u) for any value u. That is, cos is an even function 2pi - pi/4 = 7pi/4

pi + pi/6 = pi(1+ 1/6) = pi(7/6) = 7pi/6 cos(-u) = cos(u) for any value u. That is, cos is an even function 2pi - pi/4 = 7pi/4