Example 11

A Flag-post is erected on the top of a building. When a person standing at a distance of 15 m from the building looks at the top and the bottom of the flag-post, his line of vision makes an angle of elevation of 60⁰ and 45⁰ respectively. Find the height of the flag-post.

Solution

Triangle ACD is isosceles right triangle.

\ AC = DC = 15 m Now tan 60⁰ =

Example 12

What is the angle of elevation of the sun when the length of the shadow of a pole is Ö 3 times of the height of the pole ?

Solution : Let PM be the pole and its shadow is OM. Let the angle of elevation i.e. Ð POM be a

Index

3. 1 Solving Right Triangles
3. 2 Law of Cosines
3. 3 Law of Sines
3. 4 The Ambiguous Case of Law of Sines
3. 5 Areas of Triangles
Supplementary Problems

Chapter 4