An Observer Stands $1.12 \mathrm{~km}$ From a Launch Pad $19.29^{\circ}$ Three Seconds After That, the Angle the Observer Measures

Short Answer

An observer stands $1.12 \mathrm{~km}$ from a launch pad. At 12:00.00, a rocket leaves the pad and heads straight up at a constant velocity. Four seconds later, the observer measures the angle the rocket makes to the horizontal as $19.29^{\circ}$ . Three seconds after that, the angle the observer measures is $31.49^{\circ}$ . What is the speed of the rocket to the nearest metre per second?