$\"\"$

Simplify $\"\"$ .

Analysis of the voltage in a hairdryer involves terms of the form $\"\"$ .

Where,

$\"\"$ is a positive integer. \ \

$\"\"$ is the frequency of the voltage. \ \

$\"\"$ is time.

$\"\"$

Consider $\"\"$ .

Apply sine difference identity : $\"\"$ .

$\"\"$

$\"\"$ .