Calculus
posted by Mary .
An airplane is flying in still air with an airspeed of 325 miles per hour. If it is climbing at an angle of 20°, find the rate at which it is gaining altitude.

You're going to use sin = 0pposite / Hypotenuse.
In this case the hypotenuse is 325 mph, the opposite side is the gain in altitude, 20 degrees is your angle.
Therefore sin 20 = Opposite / 325 mph
sin 20 * 325 = Opposite
111.15 mph = opposite
The airplane is climbing at a rate of 111.15 mph