#### Answer

Refer to the graph below.

#### Work Step by Step

RECALL:
The graph of the function $y=a\cdot \cos{x}$:
(1) has a period of $2\pi$ and an amplitude of $|a|$; and
(2) involves a reflection about the x-axis of the parent function $y=\cos{x}$ when $a \lt 0$.
The given function has a period of $2\pi$ and since $a=-1$, its amplitude is $1$, and it involves a reflection about the x-axis of the parent function $y=\cos{x}$.
To graph the given function, perform the following steps:
(1) Create a table of values. (refer to the table below)
(2) Plot each point then connect them using a sinusoidal curve with an amplitude of $1$
Refer to the graph in the answer part above.