Chapter 2 - Acute Angles and Right Triangles - Section 2.3 Finding Trigonometric Function Values Using a Calculator - 2.3 Exercises - Page 66: 71

$\theta_2 = 48.7^{\circ}$

We can use Snell's law to find $\theta_2$: $\frac{c_1}{c_2} = \frac{sin~\theta_1}{sin~\theta_2}$ $sin~\theta_2 = \frac{c_2~sin~\theta_1}{c_1}$ $sin~\theta_2 = \frac{(2.254\times 10^8~m/s)~sin(90^{\circ})}{3\times 10^8~m/s}$ $\theta_2 = sin^{-1}(\frac{(2.254\times 10^8~m/s)~sin(90^{\circ})}{3\times 10^8~m/s})$ $\theta_2 = 48.7^{\circ}$