Airplane Flies at an Altitude of 6 Miles Towards a Point

Multiple Choice

airplane flies at an altitude of 6 miles towards a point directly over an observer. Consider $\theta$ and $x$ as shown in the following figure. The speed of the plane is 400 miles per hour.
Find $\frac { d \theta } { d t }$ when $x = 10$ . Round your answer to three decimal places.

A) $-17.647 \mathrm { rad } / \mathrm { hr }$
B) $2.941 \mathrm { rad } / \mathrm { hr }$
C) $17.647 \mathrm { rad } / \mathrm { hr }$
D) $0.044 \mathrm { rad } / \mathrm { hr }$
E) $- 8.824 \mathrm { rad } / \mathrm { hr }$