## Trigonometry (10th Edition)

$\theta=1^{\circ}$
1. Secant and cosine are reciprocals $\sec\theta=\frac{1}{\cos\theta}$ 2. Rewrite secant as cosine $\cos(5\theta +3^{\circ})=\cos(2\theta+6^{\circ})$ 3.Since the cosine values are equal, the angles themselves must be equal. $5\theta -2\theta= 6-3$ $3\theta=3$ $\theta=1^{\circ}$