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    Three C3 questions below. Just want to see if i got the same answers.

    3a) Binomial

    1-x^2 ( all square-rooted)
    Up to and including the x^4

    b) |lnx|=3

    Find the exact values of x.


    7a) Identity

    cosec^2θ + sec^2θ = cosec^2θsec^2θ


    b) 3tan^2θ-5secx +1 =0 between -π<θ(less than or equal)π



    Finally

    8i) Cartesian

    x=3 - 1/sinθ y=2sinθ




    All help is appreciated.
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    3)b)  x=e^3, e^{-3}
    8)i)  x=3-\frac{1}{y/2}=3-\frac{2}{y}
     y=\frac{2}{3-x}



    the rest are too long to write up! :p:
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    Anyone try to do question 7a+b?
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    part a) 1 / sin^2x + 1/cos^2x

    cos^2x + sin^2x / sin^2xcos^2x


    i've started you off there for a, i've re-write cosec and sec in terms of sin and cos. and then cross multiplied

    for part b) tan^2x + 1= sec^2x is all you need to know, learn those identities!!!

    Spoiler:
    Show
    a) sin^2x + cos^2x =1
    b) 3sec^2x -5secx-2=0 solve this as a quadratic
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    (Original post by devan5)
    part a) 1 / sin^2x + 1/cos^2x

    cos^2x + sin^2x / sin^2xcos^2x


    i've started you off there for a, i've re-write cosec and sec in terms of sin and cos. and then cross multiplied

    for part b) tan^2x + 1= sec^2x is all you need to know, learn those identities!!!

    Spoiler:
    Show
    a) sin^2x + cos^2x =1
    b) 3sec^2x -5secx-2=0 solve this as a quadratic

    See for part a) could you do this as a way:

    Take r.h.s

    (1 + cos^2x/sin^2x)(1 + sin^2x/cos^2x)

    Then times it out to get:

    1 + sin^2x/cos^2x + cos^2x/sin^2x + cos^2xsin^2x/cos^2xsin^2x

    Which can cancel to give the answer?

    (1 + tan^2x) + (1 + cot^2x)
    (sec^2x) + (cosec^2x)


    ??
 
 
 
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Updated: January 16, 2010
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