Show that simple harmonic motion y(t) = c1 cos ωt + c2 sin ωt can be written as: (a) y(t) = a sin(ωt + φ0); (b) y(t)= a cos(ωt + ψ0) . show that the motion given by first question can pass through the equilibrium point at most once. how many times can the motion change directions?