Question

The lenght of shadhow of a tree is 8m long sun angle elevationis 45

Answer 1

using tan ø = side opp./side adj.
tan 45°=height of tree/8m
tan 45°=1

1=height/8
height=8m

Answer 2

Consider a right angled triangle ABC, right angled at B. Now let AB be the tree (AB = 18m) and BC be its shadow. Refer the attachment.

Now according to the question, we have <C = 45 (as angle of elevation of sun is 45 degrees)
Thus we have tan45 = AB/BC
or, 18/BC = 1
or, BC = 18m
Now as BC = 18m, length of shadow = 18 metres.

Hope that helps !!