Alternate Forms for sinusoidal Oscillations: To derive the conversion formulas (7) and (8), use the identity cos(a

Question:

Alternate Forms for sinusoidal Oscillations: To derive the conversion formulas (7) and (8), use the identity
cos(a - () = cos a cos ( + sin a sin (
From trigonometry to show that the family of sinusoidal oscillations A cos(W0t -() can be written in the form
c1 cos w0t + c2 sin (0t.
Where c1 = A cos ( and c2 = A sin (.