Write an equation for a transformed cosine wave that has the following properties:
amplitude = 3
period pi
horizontal shift = none
vertical shift = 4 units up
starting with y=cosx, we get
amplitude 3: y = 3cosx
period π: y = 3cos(2x) .... since cos(kx) has period 2π/k
up 4: y = 3cos(2x)+4