trigo
posted by jayson austria on .
from the top of 90 meters high building it is observe that the top of another building make a 40 degree angle depression. if two buildings 75 meters apart how tall is the other building?

Draw a diagram. If the top of the 90m tower is A, the top of the shorter building is B, draw a horizontal line from B to the 90m tower. Label the intersection C.
Now, ABC is a right triangle, and angle A is 45°. The difference in heights is side b. The distance between the buildings is a.
a/b = tan 50° = 1.192
b = 75/1.192 = 62.92m
So, the shorter building is 9062.92 = 27.08m tall. 
oops A is 50° (90°  angle of depression)