Question

A person standing on the bank of a river observes that the angle subt ended by a tree on the opposite bank is 60° ;when he retires 20m from the bank,he finds the angle to be 30°.find the height of the tree and breadth of the river

Answer 1

tan60° = BC /AB and tan 30°=BC/DB
√3= h/x and 1/√3 =h/x+20
it gives 3x=x+20
x=10
x=10 so h= √3x
h=10√3 =17 .32
hence hieght of tree is 17.32 and breath of river is 10m