# Precalculus Examples

Subtract from .

The resulting angle of is positive, less than , and coterminal with .

Since the angle is in the third quadrant, the reference angle formula is .

To write as a fraction with a common denominator, multiply by .

Write each expression with a common denominator of , by multiplying each by an appropriate factor of .

Combine.

Multiply by .

Combine the numerators over the common denominator.

Simplify the numerator.

Multiply by .

Subtract from .