## Precalculus (6th Edition) Blitzer

$cos\theta$ and $sec\theta$
For an angle $\theta$ in quadrant IV, we have $x\gt0, y\lt0$; thus $cos\theta=\frac{x}{r}\gt0$ and $sec\theta=\frac{r}{x}\gt0$. The answers are $cos\theta$ and $sec\theta$