Sections:

Transformations of Trigonometric Functions, Page 7

Example

What would happen to the graph of f(x) = 2sin(x/3) if the 2 was negative? 

f(x) = -2 sin(x/3)

graphs of f(x) = 2 sin(x/3) and f(x) = -2 sin(x/3)

Notice that the blue graph of f(x) = -2 sin(x/3) is the mirror image (about the x-axis) of the red graph of f(x) = 2 sin(x/3).