# Calculus

posted by
**Nikki**
.

(Another related rate question)

A plane (alt. 4000ft) is flying west at 700ft/sec. A searchlight under its path, tracks it. How fast if the light pivoting when the plane is 1000ft east?

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Kind of similar to the lamp post question I posted earlier. I know dp/dt, 700ft/sec. We're looking for the rate of the light, dl/dt. 4000ft is a constant. I also think p would be -1000ft, but I'm not quite sure.

Again, I'm not quite sure about the equation. I do know, based on my picture, that there will be trig functions involved, based on the angle of the searchlight moving to track the plane. Help again?

Thanks!