UPSC NDA I 2015 Mathematics Solved Paper

Let AB denote the height of the tower.
Let BC denote the distance from the base of the tower.
Then triangle ABC is a right angled triangle, right angled at B which is the base of the tower.
Applying trigonometric identities,we get
tan C
= tan 45°
=

AB

BC

=

H

20

tan45°=

H

20

H=20tan45°
=20
Hence the height of the tower is 20 meters