a rocket is launched vertically from a point on level ground that is 3000 feet from the observer with binoculars. if the rocket is rising vertically at the rate of 750 ft/s at the instant it is 4000 above the ground, how fast must the observer change the angle of elevation of her line of sight in order to keep the rocket in sight at that instant?

did theta= (1/(1+(x/3000)^2)(dx/dt) exactly like the formula for tan(theta) x/y instructs you to.

I get .1405 when I rationalize and when I don't 270 for d(theta)/dt

Niether of which is the correct answer.

Question

a rocket is launched vertically from a point on level ground that is 3000 feet from the observer with binoculars. if the rocket is rising vertically at the rate of 750 ft/s at the instant it is 4000 above the ground, how fast must the observer change the angle of elevation of her line of sight in order to keep the rocket in sight at that instant?

did theta= (1/(1+(x/3000)^2)(dx/dt) exactly like the formula for tan(theta) x/y instructs you to. 

I get .1405 when I rationalize and when I don't 270 for d(theta)/dt

Niether of which is the correct answer.