#Trig Ratios (Cosine Rule)

34 messages · Page 1 of 1 (latest)

fast dagger
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I have understood the main steps that has been taken and my mistake was making x^2 positive when it was key not to do that. Also i was meant to make the cosine equation

b^2=a^2+c^2-2bcCosB

NOT

a^2=b^2+c^2-2bcCosB

Is it because the side that's labelled B contains the angle and we are meant to stick with that? if not can someone explain please

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wise wasp
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Yes the sides that are in the equation must be the two that have the angle in between them

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And the subject of the formula is the side opposite to the angle

fast dagger
fast dagger
wise wasp
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Lets set a letter to each side

fast dagger
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icl i was deeping it it didnt change my working

wise wasp
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Let AB=a BC=b AC=c

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c must be the subject

fast dagger
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so cant we lable C as A

wise wasp
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We can yea

fast dagger
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ok so thats fine then its not an issue

wise wasp
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But here you got a point A

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So it might be confusing

fast dagger
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so what would you do?

wise wasp
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I always name the sides that got the angle in between them a and b

fast dagger
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if they gave you ABC would you just make the respected value the subject?

wise wasp
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And the one im tryna get c

fast dagger
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so thats in this case or every case?

wise wasp
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what you name the sides doesn't matter

fast dagger
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other than the angle one

wise wasp
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Wdym

fast dagger
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so in this question A and C dosent matter

wise wasp
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Why r you so concerned with what you name each side

fast dagger
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its B that matters

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Na i said i deeped it ages ago

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meaning its not that deep

fast dagger
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cuz thats not why i got it wrong

wise wasp
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Oh alright then

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So you get the rule itself or not

fast dagger
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yeah i do

wise wasp
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So you're good