This is trigonometry:

Question

A tree's height is unknown so we have to solve for the height of the tree. The tree casts a 11m shadow. And the angle of the triangle is 36 degrees.

Answer 1

Sorry 34 degrees!!!!

Answer 2

Assuming you made a sketch, and the 34° angle is at the end of the shadow, then

h/11 = tan34
h = 11tan34
= ...