## Precalculus (6th Edition) Blitzer

$23$ cm
The trigonometric ratios are as follows: $\sin \theta= \dfrac{opposite}{hypotenuse}$ ; $\cos \theta= \dfrac{Adjacent}{hypotenuse}$ and $\tan \theta= \dfrac{Opposite}{Adjacent}$ Since, $\theta=61^{\circ}$ Then $\sin 61^{\circ}= \dfrac{20}{c}$ So, $c =20 \times \csc 61^{\circ}$ Our required answer is: $c \approx 23$ cm