An airplane is flying at an altitude of 5 miles and passes directly over a radar antenna (see figure)

radar-antenna

#1

An airplane is flying at an altitude of
5 miles and passes directly over a radar antenna (see figure).
When the plane is 10 miles away (s = 10), the radar detects
that the distances is changing at a rate of 240 miles per hour.
What is the speed of the plane?

Answer:
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