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# C2 Sine/Cosine/Bearings Question Help watch

1. Okay so if there is a * next to a number it means degree's.

Joanne walks 4.2 miles on a bearing 138*. She then walks 7.8 miles on a bearing of 251*.

a) Calculate how far Joanne is from the point where she started.

b) Find, as a bearing, the direction in which Joanne would have to walk in order to return to the point where she started.

Okay so I done a) worked it out to be 7.27 miles. I don't know if that's definitely right but you can check.
My problem is in part b). I have no clue how to do it. Any help would be appreciated. Thanks
2. Anyone?
3. if u have gotten that side,the rest should be easy.just work out the angle facing a side(i assume u dont have a problem with this).then use sine rule to work out the angle facing the 4.2 side,then work out the bearing.i worked it out to be 040.3*.
its a bit difficult for me to explain angles you cant see.so i hope by some miracle,this helps.
4. I got 7.27 miles too.

Use the sine rule to answer part B. You have all 3 sides and 1 angle, and you need to find another angle.

Draw a diagram.
5. (Original post by AnonyMatt)
I got 7.27 miles too.

Use the sine rule to answer part B. You have all 3 sides and 1 angle, and you need to find another angle.

Draw a diagram.

Okay, I drew the diagram. Is the bearing I'm trying to find the one I called y (in red) in the attachment. If so, how do I use the sine rule to work that out
Attached Images

6. (Original post by CapsLocke)
Okay, I drew the diagram. Is the bearing I'm trying to find the one I called y (in red) in the attachment. If so, how do I use the sine rule to work that out
Call side 7.27 a
So that sinA = sin67*

Now notice that y is the same angle as the one... to the left of the north line you've drawn in, opposite the side of length 7.8
Can you see where I mean?

This is because the north lines are parallel.

Anyway, call side 7.8 b
So that the opposite angle is B
You can find sinB, and therefore B

y is then B - (180-138) in degrees. Can you see why?
7. (Original post by AnonyMatt)
Call side 7.27 a
So that sinA = sin67*

Now notice that y is the same angle as the one... to the left of the north line you've drawn in, opposite the side of length 7.8
Can you see where I mean?

This is because the north lines are parallel.

Anyway, call side 7.8 b
So that the opposite angle is B
You can find sinB, and therefore B

y is then B - (180-138) in degrees. Can you see why?

Ohhh, thanks I get it now.

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