Maths

Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
Right im doing A2 maths, P3 and im stuck and need help badly!! its about double angle formulae. Can any one help???? i cant do it! :eek2:
Carrie x

Comments

  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    I'm in a similar situation, I'm doing Pure 2 and 3 alongside Statistics 2 (in which I have an exam on Friday :()

    I'm not really certain what your exact problem is? Which aspect are you stuck with?

    That's the stuff with the Sin A + B = whatever, right?

    Don't worry, I think everyone finds Maths challenging!
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    yeah its all that stuff lol i have to solve and inequailitys. The question is:
    sin2x + sinx = 0
    solve for -180 < 0 < 180

    i have a few like that and i have NO IDEA!!!!
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    Well sin2x = 2sinxcosx

    thus you have

    2sinxcosx + sinx = 0

    factorising,

    sinx(2+cosx) = 0

    2+cosx will never be 0 as cosx can only take values from 1 to -1, and even at -1 2+cosx will be 1. Thus sinx must be 0 for the solution to the equation.

    sinx = 0

    thus x = 0 is the solution.
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    Do you mind telling me, what level your math is concidered as?
    Just wanted to compare it to the Danish levels.
    Thanks.
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    That's A2 maths, which is the second tier of the A levels. We do up to GCSE's, and that's compulsory, and we HAVE to take english, maths and science. Once you get to A level, which you don't have to take, at 16, you choose 3, 4 or 5 subjects to take into further detail, and more intensively, and that has no limits on it - you can take what you like. AS, which is the first year, is considered the 'easier' part of the course, and you do that then are examined on it at the end of the year. A2 is the harder half, and you do that then are examined on it at the end of that year. Basically, it's the level just before university. *could have said that in the first place* Oh well :)

    Edited to say: Does that make sense?!
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    I had my S2 exam today. Did badly I think. But I have been wrong before. Quite annoyed because I can do Stats very well, I just hate exams.

    O well, no more until summer. Alkyhol here I come!!!!!!!!! :D
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    Originally posted by Vox populi, vox Dei
    2sinxcosx + sinx = 0

    factorising,

    sinx(2+cosx) = 0

    Are you sure that's how it factorises, not:

    2sinxcosx + sinx = 0

    sinx (2cosx + 1) = 0

    No?
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    Originally posted by Sa-ra-ra-ra


    Edited to say: Does that make sense?!

    If your explanation meant that she was doing maths on a higher level, then yes, it made sense.
    If she doesn't, then it... didn't :p
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    Originally posted by 1st_angel
    I had my S2 exam today. Did badly I think.

    Tell me about it! I did AQA Specification A and it was horrible. But it could've been worse, though I had no idea how to work out the probability of a Type II Error - our teacher told us we didn't need to know! :mad:

    DJP I believe your factorising is correct.
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    Jacqueline The Ripper - this is the Mathematics you would do at approximately ages 17 or 18 before going to University. It is classed as being a Higher level than standard examined Mathematics, say GCSE's.
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    I'm a 4th year physicist, and here is a little advice: Learn those double angle formulae like the back of your hand, I've lost count of the number of times I've had to use those.

    DJP's factorisation was correct.

    What the bloody hell is a type II error? Standard deviation, mean, chisquared, what happened to these in your course Alan? Prehaps the types are random and systematical errors?

    Are any of you lot doing complex numbers and/ or vector algebra? If you're not you should read about them, thay are real handy.
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    types

    :cool:

    What are the diffent types of maths a2 or as that you can take?
    is it something like applied and pure or something?

    I have to take maths for 6 form for the course I want to get into and i really hate it.

    :mad:
  • Former MemberFormer Member Posts: 1,876,329 The Mix Honorary Guru
    i know u cant

    but from inspecition, but for sin(2x)+sin(x)=0
    x has to be 0 degrees because all parts will equal 0!
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