# Ralated Rates

• Nov 5th 2012, 12:45 PM
PhizKid
Ralated Rates
A plane flying with a constant speed of 5 km/m passes over a ground radar station at an altitude of 1 km and climbs at an angle of 30 degrees. At what rate is the distance from the plane to the radar station increasing a minute later?

http://i.imgur.com/bkCTx.png

First of all, I don't know how to determine the sides using the given information. I'm thinking the base of the triangle, but, the triangle doesn't have enough information to solve for it.

Can I assume the red line bisects the rectangle or not? Otherwise, I don't see what else I have to go on.
• Nov 5th 2012, 12:50 PM
skeeter
Re: Ralated Rates
law of cosines ...

$r_2^2 = r_1^2 + 1^2 - 2r(1)\cos(120^\circ)$
• Nov 5th 2012, 12:53 PM
PhizKid
Re: Ralated Rates
Ah, never mind, I see it. I was just having trouble with the Law of Cosines. Well, it's easy from there. I just didn't know to use the Law of Cosines