You know tangentTheta=h/4

take the derivative

sec^2 Theta * dTheta/dt= 1/4 dh/dt

you know dtheta/dt solving for dh/dt

You know sec Theta from the right triangle:
sec theta = sqrt(h^2 +16) /h

check me.

Georgina: in the future, please put the title in the subject box, in this case: calculus, or related rates, or such.

A camera, located 4 km from the launch pad, is tracking the rocket that is fired straight up. When the height of the rocket is 13 km, the camera is rotating at the rate of 3/169 radians per second. What is the speed of the rocket at that instant? Give your answer in km/sec.

Thanks for all the help.