19.20 meters
Step-by-step explanation
as the tree is vertical , it makes a 90 ° angle with the ground, so the tree, the shadow and the distance from the top of the tree to the end of the shadow make a rigth triangle
to find the missing value we can use the Pythagorean theorem, it states that the sum of the squares on the legs of a right triangle is equal to the square on the hypotenuse
so

so
Step 1
Let

b) now, replace and solve for hypotenuse

therefore, the answer is
19.20 meters
I hope this helps you