An observer on the ground is x meters from the base of the launch pad of a rocket, which is at the same level as the observer. A few seconds after the rocket takes off vertically, the observer sees it

An observer on the ground is x meters from the base of the launch pad of a rocket, which is at the same level as the observer. A few seconds after the rocket takes off vertically, the observer sees its tip at an angle of q° from the horizontal. How far above the ground is the tip of the rocket at that instant? Assume that the ground is level.