Hi Stacy M

Again a picture or diagram would help a lot. The description indicates that the shadow on the ground is 30 meters away from the bottom of the Lighthouse and the angle of elevation at the end of this distance 36 degrees. If this correctly describes your situation and you have a Right Triangle, you just need determine which ratio applies to your situation

There is only one, the one that says Tangent because

Tan 36° = Opposite/Adjacent

Notice for this one you don't need to know the hypotenuse.

Just plug in the data and solve for the Opposite side which should be your height and the height of the Lighthouse

Give that try if you have any questions please send me a message.