Chapter 2 - Acute Angles and Right Triangles - Section 2.3 Finding Trigonometric Function Values Using a Calculator - 2.3 Exercises - Page 63: 30

$\theta$ $\approx$ 30.50274879$^{\circ}$

$\sec$ $\theta$ = 1.1606249 Therefore: $\cos$ $\theta$ = $\frac{1}{\sec\theta}$ $\cos$ $\theta$ = $\frac{1}{1.1606249}$ $\cos$ $\theta$ = 0.86160481 $\theta$ = $\cos$$^{-1}$ 0.86160481 Utilizing the calculator: $\theta$ $\approx$ 30.50274879$^{\circ}$