Answer:
28.4 feet 
Explanation:
The question can be solved by using Pythagoras Theorem. 
Given:-
Height of tree :- 18 feet (Perpendicular)
length of shadow :- 22 feet (Base)
To find:-
Distance of shadow from the end to the top of the tree
Solution:-
We know the Pythagoras theorem, 
Which is , H² = P² + B² 
So putting the given value , we get 
H² = 18²+22² 
H² = 324 + 484
H = √ 808 feet
H = 28.4 feet