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Math Help - proving sin and cos identities

  1. #1
    Newbie allywallyrus's Avatar
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    proving sin and cos identities

    i'm not sure im doing this right and im having trouble understanding this lesson
    what i have is:
    \cos\theta+\sin\theta \tan\theta = \displaystyle{\frac{1}{\cos\theta}}
    \cos\theta+\sin\theta\displaystyle{\frac{\sin\thet  a}{\cos\theta}}
    \cos\theta+\displaystyle{\frac{\sin^2\theta\}{\cos \theta}}
    \displaystyle{\frac{\cos^2\theta+\sin^2\theta}{\co  s\theta}}
    which would give me the correct answer but im worried i've done something incorrectly with the fractions
    also i'm kind of new to this latex thing, but the third line was giving me a syntax error and i don't know what i did wrong exactly so i took the tags off
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  2. #2
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by allywallyrus View Post
    i'm not sure im doing this right and im having trouble understanding this lesson
    what i have is:
    \cos\theta+\sin\theta \tan\theta = \displaystyle{\frac{1}{\cos\theta}}

    \cos\theta+\sin\theta\displaystyle{\frac{\sin\thet  a}{\cos\theta}}

    cos(\theta)+ \frac{sin^2(\theta)}{cos(\theta)}

    \displaystyle{\frac{\cos^2\theta+\sin^2\theta}{\co  s\theta}}

    which would give me the correct answer but im worried i've done something incorrectly with the fractions
    also i'm kind of new to this latex thing, but the third line was giving me a syntax error and i don't know what i did wrong exactly so i took the tags off
    Nope your maths is good, you just need to use the Pythagorean identity ( sin^2(x) + cos^2(x) = 1) to get to the final answer
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  3. #3
    Newbie allywallyrus's Avatar
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    oh good, thats what i was hoping to hear
    and i dont suppose there is any rule against bumping this thread with new questions a little later on? i will probably have a couple more
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