Chapter 11 - Section 11.3 - The Tangent Ratio and Other Ratios - Exercises - Page 511: 7

$\sin\alpha=\frac{a}{c}$ $\cos\alpha=\frac{b}{c}$ $\tan\alpha=\frac{a}{b}$ $\csc\alpha=\frac{c}{a}$ $\sec\alpha=\frac{c}{b}$ $\cot\alpha=\frac{b}{a}$

$\sin\alpha=\frac{opposite}{hypotenuse}=\frac{a}{c}$ $\cos\alpha=\frac{adjacent}{hypotenuse}=\frac{b}{c}$ $\tan\alpha=\frac{opposite}{adjacent}=\frac{a}{b}$ $\csc\alpha=\frac{hypotenuse}{opposite}=\frac{c}{a}$ $\sec\alpha=\frac{hypotenuse}{adjacent}=\frac{c}{b}$ $\cot\alpha=\frac{adjacent}{opposite}=\frac{b}{a}$