a. $y= 2sin(x)$ b. See graph.
Work Step by Step
a. Using the Sum Formula, we have $y=cos(x)cos(\pi/2)+sin(x)sin(\pi/2)-cos(x)cos(\pi/2)+sin(x)sin(\pi/2)=2sin(x)$ b. We can graph the new function $y=2sin(x)$ and compare with the given graph to see that they are identical.