A bird is flying above a tree. You are standing 40 feet away from the tree. The angle of elevation to the top of the tree is 32°, and the angle of elevation to the bird is 42°. What is the distance from the bird to the top of the tree?
Let
A -----> you
B-----> a bird
C-----> top of the tree
see the following image
step 1
In the right triangle ABD
tan(42)=BD/AD
substitute given values
tan(42)=BD/40
BD=40*tan(42)
BD=36 ft
step 2
In the right triangle ACD
tan(32)=CD/AD
CD=AD*tan(32)
CD=40*tan(32)
CD=25 ft
step 3
Find the difference BD-CD
36-25=11 ft
therefore
the answer is 11 ft