Problem: Bill is launching a model rocket. He stands 30 feet away from the launch pad, and launches the rocket. Using a string hung on a protractor, he measures the angle to the rocket at apogee to be 70 degrees. To the nearest foot, what is the aproximate maximum altitude achieved by the rocket?

Solution: First, set up a diagram of the problem.

Since we are using an angle, and using the length of one leg to find the length of another leg, we will use the "tangent" trigonometric function. Remembering that tangent is the ratio of the opposite side to the adjacent side, and using "x" for the unknown, we set up the equation like so:

tan(70 deg) = x / 30

Then solve for the unknown:

30 * tan(70 deg) = x

Finally, type the left side into a scientific calculator to find the answer, to the number of digits specified:

30 * tan(70 deg) = approx 82 feet