Question

A 1.6 m tall girl stands at a distance of 3.2 m from a lamp-post and casts a shadow of 4.8 m on the ground. Find the height of the lamp-post by using (i) trignometric ratios (ii) property of similar triangles.

Answer 1

Let AC be the lamp post of height.

We assume that ED = 1.6 m, BE = 4.8 m and EC = 3.2 m

We have to find the height of the lamp post

Now we have to find height of lamp post using similar triangles.

Since triangle BDE and triangle ABC are similar.

Again, we have to find height of lamp post using trigonometric ratios.

In

Again in

Hence the height of lamp post is m.