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## Homework Statement

A cameraman standing at A is following the movement of a race car traveling at a speed of 30 m/s. Determine the angular rate (theta dot) at which the man must turn to keep the camera directed on the car at theta = 30 degrees.

http://img143.imageshack.us/img143/8043/ohohohfc9.th.png [Broken]

b = 20 m

a = 20 m

theta = 30 degs

## Homework Equations

vr = r dot

vtheta = r*theta dot

## The Attempt at a Solution

If only I knew r dot, I could figure this problem out.

I found r with the law of cosines (r = 34.641 m).

I was thinking of using

30 = sqrt( (rdot)^2 + r^2(thetadot)^2)

but I don't know r dot... where can I find the rate of change in r?

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