Question

Write a sine equation to represent y=-2cos(4x-pi)+2

Answer 1

cos (a-b) = cos a cos b+sin a sin b

y = -2 [ cos 4x cos pi + sin 4x sin pi] +2
but sin pi = 0 and cos pi = -1
y = 2 cos 4 x +2 = 2 sqrt (1 - sin^2 4x) + 2