on the a axis, you set the x value at 0, π/4, π/2, 3π/4, π
2sin0=0, 2sin(π/2)=2, 2sinπ=0, 2sin(3π/2)=-2, 2sin(2π)=0
so the y values are 0, 2, 0, -2, 0 respectively
locate the points and connect
extend the pattern left and right if there is no limit for x. It should look like a wave