For the function y = -2+5sin(pi/12(x- what is the maximum value?

To get the function y = -2+5sin(pi/12(x-2)), the maximum value can be determined by differentiating the function and equating it to zero. The value of x will give the maximum value of the function.
dy/dx = 5 cos (pi/12 (x-2)) (pi/12)
dy/dx = 5 pi/12 cos(pi/12 (x-2))

Equate to zero:
5 pi/12 cos(pi/12 (x-2)) =0
pi/12 (x-2) = 3pi/2
x = 8

Substituting,
y= -2 + 5sin( pi/12 (8-2)
y = -1.86

Where is the diagram?