Question

a person standing on the bank of river observes that the angle of elevation of the top of a tree on the opposite bank is 60 degree when he moves 40 metre away from the bank he finds the angle of elevation to be 30degree find the height of the tree and width of the river

Answer 1

h is height of tree, CB is width of river
tan 60 = h/CB
tan 30= = h/(40+CB)

use the above equations to solve for CB and then h