Solution:

It is given that

AB is a building

CD = 60 m

In triangle ABC

tan 60⁰ = AB/BC

√3 = AB/BC

So we get

BC = AB/√3 ….. (1)

In triangle ABD

tan 30⁰ = AB/BD

1/√3 = AB/ (BC + 60)

By cross multiplication

BC + 60 = √3 AB

BC = √3 AB – 60

Using both the equations we get

AB/√3 = √3 AB – 60

By further calculation

AB = 3AB – 60√3

3AB – AB = 60 × 1.732

So we get

AB = (60 × 1.732)/ 2

AB = 51.96 m