Answer
See explanations.
Work Step by Step
Step 1. Recall the conclusion from Exercise 46: the distance from that focus to any point $P(r_p,\theta_p)$ on the conic is given by $|r_p|$
Step 2. In the case of satellite orbiting the Earth, the Earth is at the focus and the distance between the satellite and the Earth can be easily found as $|r_p|$ when we use a polar system with the satellite at $P(r_p,\theta_p)$.
Step 3. If we use a rectangular system, we will need to find the coordinates $P(x,y,z)$ which requires the measurement of three quantities $x,y,z$ before we can calculate the distance of the satellite to the Earth.
