This problem sets up the information necessary to solve for the height of a building using a clinometer. Using tangent to solve for the height of the building is the most obvious method, but since the angle of elevation is 30 degrees, it is possible to use special right triangles as well. Be sure to account for the eye level. You can leave questions and/or solutions in the comments if you like. The app I used to measure the angle is called "Clinometer + bubble level" (I have an Android phone, so I am not sure if it available for iPhones).