Question

Please illustrate to me how -3 cos pi/2 = 0?

Answer 1

look at a unit circle at 9"oclock is 1 pi right
well pi over 2 is then at 12"oclock
on a cartetion plane (normal grid ) (0,1) is the location
we know that cos is X and sin is y
so the of the location at 12'oclock is pi/2 ->(arccos(0),arcsin(1))