# Precalculus Examples

Find an angle that is positive, less than , and coterminal with .
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 .
Simplify the right side of the equation .
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 .