precalc math problem

Question

Seth is standing 60 feet from a roadway. He observes a car that is speeding, and estimates an observation angle of 60 degrees from the time the car is even with him to a point where the car is 1 second later. How fast was the car going? (in mph)

Answer 1

Draw a figure to see that in the 60-30 right triangle, this distance traveled is 60*√3 feet,

i.e. 60√3 feet/sec.

Now convert ft/sec to mph (multiply by 3600/5280)...and if you can't figure out why this is so, please contact me.