<span lang="EN-US

Let BC be height of the tree.

AB be the breadth of the river.

A be the initial position of the person

D be the final position of the person

∠CAB = 60° & ∠CDB = 30° & DA = 40m

Let AB = x & BC = h

In Δ DBC

⇒

⇒

⇒ ……. (1)

In Δ ABC

⇒

⇒

⇒ …… (2)

Using (1) & (2)

⇒

⇒

⇒

⇒

⇒ AB = 20m

⇒ BC =20√3 m =20×1.73 =34.6m

∴Height of the tree is 34.6m and width of the river is 20m.