From diagaram
AB = tower = ?
CB = canal = ?
From right ΔABD,
tan 30° = AB/BD
1/√3 = AB/(20+BC)
AB = (20+BC)/√3 … (i)
Also,
In right ΔABC,
tan 60° = AB/BC
√3 = AB/BC
AB = √3 BC … (ii)
From equation (i) and (ii)
√3 BC = (20+BC)/√3
3 BC = 20 + BC
2 BC = 20
BC = 10
Substituting the value of BC in equation (ii)
AB = 10√3
This implies, the height of the tower is 10√3 m and the width of the canal is 10 m.