trigonometry i dont get it

Question

A building casts a shadow of 100 feet. The angle of elevation from the end of the shadow to the top of the building is 15 degrees. Approximately how tall is the building to the nearest whole number?

Answer 1

construct a right triangle where 90 degrees is the angle between the building and the ground

tangent of the angle where the shadow ends = opposite side over adjacent side = h/100

tangent of 15 degrees = height of the building divided by 100 feet

tan15 = h/100

height = h = 100tan15

= 100(0.2675) = 26.795 feet high

= about 27 feet