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    Every time i make a thread i always end up being able to work them out haha
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    For the first question, what are the two values you have?

    For the second, can you make the equation into a quadratic in cos(x)?
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    (Original post by eatingkiwi)
    Solve 2sin^2x = 5cosx + 4 between 0 and 360 degrees.
    I have no idea how to go about this one.

    Please could somebody explain what to do?
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    For the first one you should have gotten a quadratic with 2 roots. That will give you 4 answers by the end.

    For the second one you want sin^2x+cos^2x=1
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    Solve 2sin^2x = 5cosx + 4 between 0 and 360 degrees. I have no idea how to go about this one.
    sin^2x+cos^2x=1

    2(1-cos^2x) = 5cosx + 4
    if X=cosx
    then -2X^2-5X-2=0
    delta=25-4*-2*-2=3^2
    then X1=... and X2=... then x=....
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    (Original post by dguess499)
    Solve 2sin^2x = 5cosx + 4 between 0 and 360 degrees. I have no idea how to go about this one.
    sin^2x+cos^2x=1

    2(1-cos^2x) = 5cosx + 4
    if X=cosx
    then -2X^2-5X-2=0
    delta=25-4*-2*-2=3^2
    then X1=... and X2=... then x=....
    Can you solve the quadratic -2X^2 - 5X -2 = 0?
 
 
 
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