In Exercises, graph the function if the given changes are made in the indicated examples of this section.

In Example 3, if the sign before π/6 is changed, sketch the graph of the resulting function.

Data from Example 3

Sketch the graph of the function y = −cos(2x + π/6).

First, we determine that
1. The amplitude is 1
2. The period is 2π/2 = π.

3. The displacement is −π/6 ÷ 2 = −π/12.

We now make a table of important values, noting that the curve starts repeating π units to the right of −π/12.

From this table, we sketch the graph in Fig. 10.17.

X y - 1 5 2 1 0 - 1 2 6 0 - - (period) = - :