Fitzpatrick Question-Trig (1 Viewer)

[rajeenth]

can some one please tell me how 2 do question twelve of chapter 21. Applied trig.

 

[SoulSearcher]

It might be useful to post the question up as well, for those who don't have access to that book.

 

[rajeenth]

sorry ..heres the question
A and B are two towers, B being 4 KM due east of A. The true bearings of a flagpole,C, from A and B are (alpha) east of north and (alpha) west of north respectively. The true bearings of a second flagpole,D, from A and B are ((alpha)+(beta)) east of north and ((alpha)-(beta)) west of north respectively. Draw a sketch to indicate the positions of A, B, C and D. Assuming A,B,C,D are on level ground, and that (alpha)=25 and (Beta)=10, find distance between C and D.

 

[rajeenth]

can anyone tell
where can i get the solution of three unit course for years 11 & 12 j.b fitzpatrick
thanks

 

[lyounamu]

can anyone tell
where can i get the solution of three unit course for years 11 & 12 j.b fitzpatrick
thanks

It's very hard to find and I doubt you will find though. I have written all my solutions by myself so I can post them up here but there are just too many pages to post up. So, I will give you solution for any question you put up (any question in chapter 21 as I have already done every single one of them). I am sorry that I cannot post them up, it is just too difficult to post 30 pages of hand-written notes.

EDIT: JUST quote the number of question (also mention the chapter or name of exercise e.g. 2(a) question 21)

 

[lyounamu]

sorry ..heres the question
A and B are two towers, B being 4 KM due east of A. The true bearings of a flagpole,C, from A and B are (alpha) east of north and (alpha) west of north respectively. The true bearings of a second flagpole,D, from A and B are ((alpha)+(beta)) east of north and ((alpha)-(beta)) west of north respectively. Draw a sketch to indicate the positions of A, B, C and D. Assuming A,B,C,D are on level ground, and that (alpha)=25 and (Beta)=10, find distance between C and D.

You have to draw the diagram. If you draw it yourself, it will look like 2-dimensional diagrams of 2 triangles with the peaks called C and D.

So when you draw this diagram. Just draw 2 triangles (overlapping in the centre, I will call it E).

Using the sine rule, 4km/sin60 = BE/sin 55
Therefore, BE = 3.78350122...
Now, BE/sin 50 = DE/sin 10
Therefore, DE = BE/sin 50 x sin 10
= 3.78350122.../sin 50 x sin 10
=0.857650099...
Now, DE/sin 55 = CD/sin 60
Therefore, CD = 0.906726387....
Therefore, CD = 0.9067 km (to 4 decimal places).

I am sorry if I explained poorly. However, this question is too diagram-based and you need to be able to visualise how the diagram looks like and from that, you solve the question out. I will try posting my diagram up but my camera is broken :mad1: (I am really sorry). I hope that someone posts his/her diagram up.

 

[rajeenth]

thanks
but probelem is two angles are (alpha)how could be a true bearing?that is my doubt?
true bearing means that should be clock wise?do u understand what i mean?

 

[lyounamu]

thanks
but probelem is two angles are (alpha)how could be a true bearing?that is my doubt?
true bearing means that should be clock wise?do u understand what i mean?

No, it's not a true bearing. They didn't say in the question, or did they? If you look at the question they included the direction like 'east of north' or 'west of north'. From that, I drew the two triangles that partially overlap.

EDIT: I meant the true bearing as in T100 degrees. They give you directions such as north south. You should know how to draw the diagram from the directions given.

 

[rajeenth]

yea it does say true bearing. thats wat put me off.

 

[lyounamu]

yea it does say true bearing. thats wat put me off.

Directions are given as well so what is confusing you? True bearing is not necessarily T100 degrees (as an example). It can be north east or south east (as in direction).

 

[Tsylana]

It's very hard to find and I doubt you will find though. I have written all my solutions by myself so I can post them up here but there are just too many pages to post up. So, I will give you solution for any question you put up (any question in chapter 21 as I have already done every single one of them). I am sorry that I cannot post them up, it is just too difficult to post 30 pages of hand-written notes.

EDIT: JUST quote the number of question (also mention the chapter or name of exercise e.g. 2(a) question 21)

You only got 30 pages? ><" I got something like 360 ><"
Worked solution to every question in the book 2u book plus a few of the 3u stuff..? ><"

 

[lyounamu]

You only got 30 pages? ><" I got something like 360 ><"
Worked solution to every question in the book 2u book plus a few of the 3u stuff..? ><"

I was talking one chapter by the way. :uhhuh: