Mimi_x3
Amy is 20m S30°W from a tree. Belinda is 50m 110° T from the same tree. Find the distance between them, to the nearest metre.



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fiddlearound
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what do S30°W and 110° T mean ?

Mimi_x3
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Um, I'm not sure but i think South 30 degrees West , 110 degrees true bearing idk. I haven't done it in ages so I forgot xD

fiddlearound
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dw:1315630919336:dw

fiddlearound
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like that ^^^ ?

fiddlearound
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dw:1315631114054:dw

Mimi_x3
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Um, idk , it looks right though xDD

Mimi_x3
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How can I find the distance between them ?

fiddlearound
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dw:1315631564224:dw

Mimi_x3
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Um, I don't think that it requires sin and cos, its bearings

fiddlearound
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dw:1315631903573:dw

Mimi_x3
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What? There's not values of x and y, how can you use the distance formula ?

fiddlearound
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I got the values of x and y using the sin() and cos() in the table I drew above.
Rounded to the nearest metre, I get 64 meters distance.

Mimi_x3
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Okay, tyvm (:

fiddlearound
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does it make sense ?
did you learn this stuff in the past ?

Mimi_x3
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Not in the past xD, I learnt it year 7 and now I forgot xD
But I remember that there's an easier way that doesn't require sin and cos

fiddlearound
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Well , if there is an easier way, I hope someone will post it here  coz I'd like to know it too :)

Mimi_x3
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Hey, you know your diagram what is the angle degrees thing for AB

fiddlearound
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what do you mean ?

Mimi_x3
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dw:1315632702671:dw

fiddlearound
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yes we can calculate that  it's 240110 = 130 degrees

fiddlearound
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and you're right that we can make the problem simpler

Mimi_x3
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Yep, there's a formula to calculate it then, was it the sine or cosine formula ? or was it soh cah toa ?

fiddlearound
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dw:1315633004738:dw

Mimi_x3
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dw:1315634036159:dw

fiddlearound
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I would need to calculate to find out  why are you asking ?

Mimi_x3
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If that angle can be found, then I can use the sine rule xD

fiddlearound
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are you trying to use the law of the cosines ?

Mimi_x3
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No, the Sine Rule it says it in my book xD

fiddlearound
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which sine rule ?
a/sin(A)=b/sin(B)=c/sin(C)
?

upsilon
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Yes, that's it @fiddle

Mimi_x3
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Yep that xD

fiddlearound
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yes, but we only have one angle , that 130 degrees at this point.

Mimi_x3
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I know , but the other angle is 30 right ? the one that I drew

fiddlearound
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why did you pick 30 degrees ?

fiddlearound
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is it becasue sin(30)=1/2 ?

Mimi_x3
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Well, the question S30°W so that angle is 30 right ?

fiddlearound
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dw:1315634688115:dw

upsilon
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No, you can't say that...@mimidw:1315634688202:dw

fiddlearound
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The 30 degrees would be relative to the black line I drew.

fiddlearound
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yeah, upsilon says the same thing.

Mimi_x3
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Can it be 60 then, since 9030 = 60 ?

upsilon
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You can't decide like that you need the angle to be in ratio with the opposite sides...

fiddlearound
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yep

fiddlearound
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but the law of the cosines might work here.


upsilon
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Yea, that will work

fiddlearound
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dw:1315635067683:dw

upsilon
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\[d = \sqrt{ a^2 + b^2  2*a*b*cos\alpha}\]

Mimi_x3
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Okay, tyvm (:


Mimi_x3
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Ok, ty (:

fiddlearound
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and it's much shorter than the first method :)

Mimi_x3
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yup xD. Your method looked so complicated before (: