Question

a 18 foot ladder is placed against a building so the angle between the ground and the ladder is 82 degrees. how high does the ladder reach on the building?

Answer 1

After reviewing the basic trig ratios of right-angled triangles, you will see that
height/18 = sin82°
height = 18sin82° = ...

Answer 2

Draw a diagram and review your basic trig functions. It should be clear that the height h can be found using

h/18 = sin82°