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Not sure if i've got the trig functions correct

  1. Sep 7, 2008 #1
    I'm doing A2 Edexcel maths and i keep on forgetting the trig functions so can someone take a look and tell me if i've got it right.

    So far:





    this is where i get abit stuck

    (sin^2(x)+cos^2(x)=1)/cos^2(x) = tan^2(x)+1=sec^2(x)

    (sin^2(x)+cos^2(x)=1)/sin^2(x) = tan^2(x)+1=sec^2(x)

    i'm not sure if i've got them wrong or if i'm meant to divide by sin(x) or sin^2(x)

    Please help me :smile:
  2. jcsd
  3. Sep 7, 2008 #2
    just looked and i dont think i should have divided by sin^2(x) because the powers on sin/cos would be wrong.... i think
  4. Sep 7, 2008 #3
    [tex]\frac{a^2}{b^2} = (\frac{a}{b})^2, b \neq 0[/tex]
  5. Sep 7, 2008 #4


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    tan = sin/cos.

    1st equation here looks good.
    2nd equation: you get a cos/sin term, that is not = tan.
  6. Sep 7, 2008 #5


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    Hi groom03! :smile:

    hmm … how to remember trigonometric identities … ? :rolleyes:

    I always find that the safest plan is to write down what I think the formula is, and then multiply by cos2 or sin2 to check it.

    For example, if I get confused :confused: and think cosec2 + cot2 = 1, then I multiply by sin2 and get 1 + cos2 = sin2 … which it isn't! :wink:
  7. Sep 8, 2008 #6

    i keep on getting sin/cos and cos/sin wrong, and i just realised the second equation should equal cosec^2(x).

    Thanks for your help
  8. Sep 8, 2008 #7


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    I am guessing that this is a typo. You surely mean:

    [tex] \sin^2(x) + \cos^2(x) =1 [/tex]
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