Learning Objectives
By the end of this section, you will be able to:
- Use right triangles to evaluate trigonometric functions.
- Find function values for [latex]30^\circ \left(\frac{\pi }{6}\right)[/latex], [latex]45^\circ \left(\frac{\pi }{4}\right)[/latex], and [latex]60^\circ \left(\frac{\pi }{3}\right)[/latex].
- Use cofunctions of complementary angles.
- Use the deļ¬nitions of trigonometric functions of any angle.
- Use right triangle trigonometry to solve applied problems.
We have previously defined the sine and cosine of an angle in terms of the coordinates of a point on the unit circle intersected by the terminal side of the angle:
[latex]\begin{array}{c}\cos \text{ }t=x\\ \sin \text{ }t=y\end{array}[/latex]
In this section, we will see another way to define trigonometric functions using properties of right triangles.