## Mimi_x3 5 years ago An electricity tower is h metres high. The elevation angles of the tower from Aaron and Kevin are respectively 45° and 30° . On the ground, relative to the tower the bearings of Aaron and Kevin are respectively SW and SE. If the boys are 50m apart, find the height h of the tower to the nearest on-tenth of metre. Can someone please explain, I'm so lost xD

1. Mimi_x3

idk

2. anonymous

oh

3. Mimi_x3

Do i work it out by soh cah toa ?

4. anonymous

I'll try it

5. Mimi_x3

Okay, btw I asked the question before and someone drew a different diagram to yours xD

6. anonymous

really?

7. anonymous

this problem is 3 dimensional|dw:1316171303379:dw|

8. anonymous

you are right.

9. Mimi_x3

Is it 3D ?

10. anonymous

from first two diagrams we get AT = h and KT = $h \sqrt{3}$ so from 3rd figure AT2 + KT2 = 2500 so on simplifying h = 25 m

11. anonymous

the first 2 diagrams are 2 dimensional and the 3rd figure is an overhead view

12. Mimi_x3

ohh I get it tyvm (:

13. Mimi_x3

|dw:1316171761134:dw| Is this right as well ?>

14. anonymous

but the two lines below are inclined at 90 degrees to each other in the 3rd dimension

15. Mimi_x3

So its wrong ?

16. anonymous

the figure is somewhat like .... try cutting a pyramid with a square base from one corner of base to it's opposite corner symmetrically. then u get a figure similar to what we need (not exactly similar but good enough to understand the above problem)

17. Mimi_x3

So the figure I drew was wrong ?:

18. anonymous

|dw:1316172253129:dw|

19. Mimi_x3

oh 3D trig ?

20. anonymous

the above figure is possible only in 3d

21. Mimi_x3

it can be in 3D ?

22. anonymous

no no u don't need 3d trig. just consider each triangle at one time to get the required variables

23. Mimi_x3

Okay, but is it necessary though to draw it ?

24. anonymous

the whole point is to test whether u can imagine the required diagram once u get the diagram it is easy simplification. u can see that i used the first two diagrams to get the values of AT and KT in terms of h and then used pythagoras theorem in the final triangle. drawing the diagram is important unless u can visualize it exactly to solve the problem in ur head

25. Mimi_x3

Okay tyvm (: