## Precalculus (6th Edition) Blitzer

Let $\theta$ be any angle in standard position and let $p=\left( x,y \right)$ be any point besides the origin on the terminal side of $\theta$. If $r=\sqrt{{{x}^{2}}+{{y}^{2}}}$ is the distance from $\left( 0,0 \right)$ to $\left( x,y \right)$ , the trigonometric functions of $\theta$ are defined as follows: \begin{align} & \sin \theta =\underline{\frac{y}{r}}\text{ }\csc \theta =\underline{\frac{r}{y}} \\ & cos\theta =\underline{\frac{x}{r}}\text{ }\sec \theta =\underline{\frac{r}{x}} \\ & \tan \theta =\underline{\frac{y}{x}}\text{ cot}\theta =\underline{\frac{x}{y}} \\ \end{align}.