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    (Original post by rachelc142)
    Would anybody mind helping with a c3 trig question

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    Sure thing.
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    (Original post by The Financier)
    Sure thing.
    Thankyou

    So its
    'Solve 2cot(^2)3theta=7cosec 3theta -5 for 0-theta-180deg'

    Basically I tried using identities with the assumption cot^2theta +1 = cosec^2theta works for all multiples of theta

    So I let cot(^2)3theta =cosec (^2)3theta -1
    Multiplied the bracket out and rearranged to get
    5cosec(^2)3theta = 3
    Square rooted and rerranged for
    Sin3theta = 5 / root15

    And was going to solve like a c2 trig question but obviously cant do that as 5/root15 > 1
    Do I need to implement multiple angle formulas? Or did I go wrong somewhere further up?
    Thanks so much

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    (Original post by rachelc142)
    Thankyou

    So its
    'Solve 2cot(^2)3theta=7cosec 3theta -5 for 0-theta-180deg'

    Basically I tried using identities with the assumption cot^2theta +1 = cosec^2theta works for all multiples of theta

    So I let cot(^2)3theta =cosec (^2)3theta -1
    Multiplied the bracket out and rearranged to get
    5cosec(^2)3theta = 3
    Square rooted and rerranged for
    Sin3theta = 5 / root15

    And was going to solve like a c2 trig question but obviously cant do that as 5/root15 > 1
    Do I need to implement multiple angle formulas? Or did I go wrong somewhere further up?
    Thanks so much

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    Latex pls T_T

    I'll give it a go now
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    (Original post by Bude8)
    Latex pls T_T

    I'll give it a go now
    Ty
    Sorry for having to type it out messily can't figure out uploading pics on here on my phone

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    (Original post by rachelc142)
    Ty
    Sorry for having to type it out messily can't figure out uploading pics on here on my phone

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    Can you use a calculator for C3?

    edit: think I've done it, I'll start typing it up.
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    (Original post by Bude8)
    Can you use a calculator for C3?
    Yeah, I'm with edexcel so not sure if its different for other exam boards but this is taken from a calc paper

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    (Original post by rachelc142)
    Ty
    Sorry for having to type it out messily can't figure out uploading pics on here on my phone

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    Rewriting the equation:

    \dfrac{2}{\tan^2 3\theta}=\dfrac{7}{\sin 3\theta}-5

    \dfrac{2 \cos^2 3 \theta}{\sin^2 3\theta}=\dfrac{7}{\sin 3\theta}-5

    Multiplying by \sin ^2 3\theta and using Pythagorean identity:

    2-2 \sin^2 3\theta=7 \sin 3\theta - 5\sin^2 3 \theta

    Set it equal to 0, and it'll factorise. I think that's how it's done.
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    (Original post by rachelc142)
    Thankyou

    So its
    'Solve 2cot(^2)3theta=7cosec 3theta -5 for 0-theta-180deg'

    Basically I tried using identities with the assumption cot^2theta +1 = cosec^2theta works for all multiples of theta

    So I let cot(^2)3theta =cosec (^2)3theta -1
    Multiplied the bracket out and rearranged to get
    5cosec(^2)3theta = 3
    Square rooted and rerranged for
    Sin3theta = 5 / root15

    And was going to solve like a c2 trig question but obviously cant do that as 5/root15 > 1
    Do I need to implement multiple angle formulas? Or did I go wrong somewhere further up?
    Thanks so much

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    I believe Bude has done it right :rolleyes:
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    (Original post by Bude8)
    Rewriting the equation:

    \dfrac{2}{\tan^2 3\theta}=\dfrac{7}{\sin 3\theta}-5

    \dfrac{2 \cos^2 3 \theta}{\sin^2 3\theta}=\dfrac{7}{\sin 3\theta}-5

    Multiplying by \sin ^2 3\theta and using Pythagorean identity:

    2-2 \sin^2 3\theta=7 \sin 3\theta - 5\sin^2 3 \theta

    Set it equal to 0, and it'll factorise. I think that's how it's done.
    Thanks so much!

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    (Original post by rachelc142)
    Thanks so much!

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    Couldn't you find the mark scheme though? :lol:
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    (Original post by Bude8)
    Couldn't you find the mark scheme though? :lol:
    The teacher gave us a booklet of c3 past paper questions but didnt put which papers each question is from
    And I seriously don't want to go through every single c3 paper to find it haha

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    (Original post by rachelc142)
    The teacher gave us a booklet of c3 past paper questions but didnt put which papers each question is from
    And I seriously don't want to go through every single c3 paper to find it haha

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    You could try googling the problem
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    (Original post by Bude8)
    You could try googling the problem
    Yeah true
    With stuff like this I'll always go to classmates first, then the student room, then examsolutions hahah

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    (Original post by rachelc142)
    Yeah true
    With stuff like this I'll always go to classmates first, then the student room, then examsolutions hahah

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    my go to --> http://math.stackexchange.com/ :lol:
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    Oooh will have to check that out

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    Has anybody done Taylor expansion yet in fp2 (edexcel)?
    Having to self teach it and finding it really tricky

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    (Original post by rachelc142)
    Has anybody done Taylor expansion yet in fp2 (edexcel)?
    Having to self teach it and finding it really tricky

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    Is it literally not just differentiating a function and subbing a value of x-a in?
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    (Original post by L'Evil Fish)
    Is it literally not just differentiating a function and subbing a value of x-a in?
    Sorry if it seems so simple to you

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    (Original post by rachelc142)
    Sorry if it seems so simple to you

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    No I'm asking :lol:
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    (Original post by L'Evil Fish)
    No I'm asking :lol:
    I might be overcomplicating it but I really don't understand it
    I have a very vague teacher and feel that I haven't understood anything so far this year
    Also haven't done differentiating trig in c3 yet so that complicates matters

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