Question

a boy is 20degree away from a tree and he observes that the angel of elevation of a bird on a tree is 55degree. he is 1point7m tall How high is the tree

Answer 1

since "20degree away from a tree" makes no sense, I will assume you meant that the boy is 20 meters away. If so, then just draw a diagram, and you can see that if the tree's height is h, then
(h-1.7)/20 = tan55°
Now just solve for h.

Answer 2

Please