# Trigonometry Examples

Solve for B (27^2-12^2-20^2)/(-2(12)(20))=cos(B)
Rewrite the equation as .
Take the inverse cosine of both sides of the equation to extract from inside the cosine.
Evaluate .
The cosine function is negative in the second and third quadrants. To find the second solution, subtract the reference angle from to find the solution in the third quadrant.
Simplify .
Multiply by .
Subtract from .
Find the period.
The period of the function can be calculated using .
Replace with in the formula for period.
Solve the equation.
The absolute value is the distance between a number and zero. The distance between and is .
Divide by .
The period of the function is so values will repeat every radians in both directions.
, for any integer