Question

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

Answer 1

Answer:

Hight of the tree =20$\sqrt{3}$ m

width of the river = 20 m

Step-by-step explanation:

draw a right angled triangle ABC ,with AC horizontal and BC vertical. mark D on the line AC such as angle CAB ,CDB is 30 and 60 respectively.

AD = 40m (given)

ADB = 180-60=120

ABD =30

Therefore, AD=DB=40

BC = BDsin60= 40* $\sqrt{3}$/2 = 20$\sqrt{3}$m  height of the tree

DC = BDcos60 = 40* 1/2 = 20m = width of the river.