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    Ok, so i know dydx (cosx) = -sinx and thus the integral of -sinx is cosx. I also know that dydx -cosx = sinx

    How can i memorise the integrals of cosx, -cosx etc. Is there any erasy wat?
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    (Original post by Axion)
    Ok, so i know dydx (cosx) = -sinx and thus the integral of -sinx is cosx. I also know that dydx -cosx = sinx

    How can i memorise the integrals of cosx, -cosx etc. Is there any erasy wat?
    If you do physics, I like to think of the integration of sinusoidal curves is the change in phase by (to the right) \frac{\pi}{2} and differentiation is the converse.
    Also there's this that I found online.
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    (Original post by Axion)
    Ok, so i know dydx (cosx) = -sinx and thus the integral of -sinx is cosx. I also know that dydx -cosx = sinx

    How can i memorise the integrals of cosx, -cosx etc. Is there any erasy wat?
    Just think of the graphs, the gradient of a sin graph is the value of the cos graph in the same place. It's hard to explain but for example, as sinx differentiates to cosx, as sinx passes through the origin it has a gradient of 1, the graph of cosx = 1 when x=0. tanx differentiates to sec^2x and I think you just remember that one
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    Don't understand a fair bit of that...

    What are the integrals of

    cosx

    and -cosx?

    Cheers
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    (Original post by Axion)
    Don't understand a fair bit of that...

    What are the integrals of

    cosx

    and -cosx?

    Cheers
    Cosx integrates to sinx
    -cosx integrates to -sinx
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    differentiate sinx and you get cosx
    so integrate cosx and you get sinx


    differentiate cosx and you get -sinx
    so integrate sinx and you get -cosx
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    I remember this way
    cosx
    -sinx
    -cosx

    as you go down your differentiating, as you go up your integrating, and just reverse the signs if you have to (eg integral of cosx would be sinx)
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    Cheers guys, repped who I could. But can't rep TenofThem as have done too recently :P
 
 
 
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