# Finding the heght with bearings

• Jun 4th 2011, 07:26 PM
Finding the heght with bearings
Bob and Shelila are standing on a road 150m apart. A tower is due north of Bob and on a bearing of 070 degrees T from Shelila. The top of the tower appears at an angle of elevation of 27 degrees to Shelila and 18 degrees to Bob.

Find the height of the tower above the road. what assumptions need to be made?

My attempt-
assumptions- the location of jack from rosa and the tower.

3 simultaneous equations:
rosa: tan18deg= h/x (i)
jack: tan27deg= h/y (ii)
3rd: 150^2=x^2+y^2 - 2xy cos 70deg (iii)

steps:
1. make h the subject in (i)
2. sub h=__ into (ii)
3. make x or y the subject
4. sub x/y=___ into (iii)
5. solve for x/y

• Jun 4th 2011, 08:30 PM
TKHunny

It might be right. Too bad we don't know what anything means.
• Jun 4th 2011, 08:50 PM
Quote:

Originally Posted by TKHunny

It might be right. Too bad we don't know what anything means.

h is height of the tower
x is the distance from jack to the tower
y is the distance from rosa to the tower
• Jun 5th 2011, 02:35 AM
TKHunny
I'd prever one more word to make these definitions clear.

x = horizontal distance from Jack to Tower, for example. This would be different from "distance from Jack to the top of the tower.

Rational thinking: Without solving the problem, who is closer to the tower? If you know this, you can rule out many errors.