Answer
a. $2.1^{\circ}$
b. $9.8^{\circ}$
Work Step by Step
$sin \theta=\frac{v_{sound}}{v_{obj}}$
a. $$\theta=sin^{-1}(\frac{v_{sound}}{v_{object}})=sin^{-1}(\frac{343m/s}{9200m/s})=2.1^{\circ}$$
b. The speed of sound in seawater is found in Table 12–1.
$$\theta=sin^{-1}(\frac{v_{sound}}{v_{object}})=sin^{-1}(\frac{1560m/s}{9200m/s})=9.8^{\circ}$$