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C3 Basic Trig Watch

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    tan2θcosec2θ
    Simplify
    I did tan2θ * 1/sin2θ = tan2θ/sin2θ
    However, it is either wrong or i have not simplified far enough?
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    is that tan2feta, or tan squared feta?
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    (Original post by DeGoldenGamer)
    is that tan2feta, or tan squared feta?
    tan 2 feta
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    (Original post by DeGoldenGamer)
    is that tan2feta, or tan squared feta?
    Big man what's feta? Lmao, You making me hungry.
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    (Original post by Desultory)
    tan2θcosec2θ
    Simplify
    I did tan2θ * 1/sin2θ = tan2θ/sin2θ
    However, it is either wrong or i have not simplified far enough?
    You didn't really simplify it, you just changed the cosec to a sin

    Given these are both functions of 2\theta, you may be expected to use the double angle formulae to change these into expressions of just \sin\theta and \cos\theta

    Give that a go and let us know what you come up with
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    (Original post by Ed5)
    You didn't really simplify it, you just changed the cosec to a sin

    Given these are both functions of 2\theta, you may be expected to use the double angle formulae to change these into expressions of just \sin\theta and \cos\theta

    Give that a go and let us know what you come up with
    This is c3 year 13 maths? Sorry i dont know the double angle formulae
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    (Original post by Desultory)
    This is c3 year 13 maths? Sorry i dont know the double angle formulae
    If you're on edexcel, aye it's C3 and these formulae are a key part of it. They let you break down trignometric functions into more basic ones, e.g. \sin(a+b)=\sin a\cos b + \sin b \cos a

    You should definitely cover it in class at some point so it's likely you just haven't reached the topic yet
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    (Original post by Desultory)
    tan2θcosec2θ
    Simplify
    I did tan2θ * 1/sin2θ = tan2θ/sin2θ
    However, it is either wrong or i have not simplified far enough?
    Write \displaystyle \tan 2\theta = \frac{\sin 2\theta}{\cos 2\theta} and see what you notice.

    You don't need to use double angle formulae for this question.
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    (Original post by Ed5)
    If you're on edexcel, aye it's C3 and these formulae are a key part of it. They let you break down trignometric functions into more basic ones, e.g. \sin(a+b)=\sin a\cos b + \sin b \cos a

    You should definitely cover it in class at some point so it's likely you just haven't reached the topic yet
    That is true but this is a section 6 question which is basic trig not section 7 which is further trig so i am not expexted to use that so i need another way?
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    (Original post by Notnek)
    Write \displaystyle \tan 2\theta = \frac{\sin 2\theta}{\cos 2\theta} and see what you notice.

    You don't need to use double angle formulae for this question.
    i know tan theta = sin theta / cos theta but if its tan 2 theta, are you allowed to put a 2 infront of the sin and cos theta?
    I didnt know that?
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    (Original post by Desultory)
    i know tan theta = sin theta / cos theta but if its tan 2 theta, are you allowed to put a 2 infront of the sin and cos theta?
    I didnt know that?
    Yes, the identity is \displaystyle \tan A \equiv \frac{\sin A}{\cos A} , \ \cos A \neq 0 \ \ and since it's an identity, it's true for all A so you can replace A with anything.

    E.g. \displaystyle \tan 22 = \frac{\sin 22}{\cos 22}

    or \displaystyle \tan 2\theta = \frac{\sin 2\theta}{\cos 2\theta}
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    (Original post by Desultory)
    That is true but this is a section 6 question which is basic trig not section 7 which is further trig so i am not expexted to use that so i need another way?
    (Original post by Notnek)
    Write \displaystyle \tan 2\theta = \frac{\sin 2\theta}{\cos 2\theta} and see what you notice.

    You don't need to use double angle formulae for this question.
    Must just be like this then. I wasn't really sure given you didn't mention the module, and 'simplify' can be quite open ended
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    (Original post by Notnek)
    Yes, the identity is \displaystyle \tan A \equiv \frac{\sin A}{\cos A} (\cos A \neq 0) and since it's an identity, it's true for all A so you can replace A with anything.

    E.g. \displaystyle \tan 22 = \frac{\sin 22}{\cos 22}

    or \displaystyle \tan 2\theta = \frac{\sin 2\theta}{\cos \theta}
    Okay that makes sense thanks i worked it out now
    However, if there is a question where its tan^2 theta, can that equal sin^2 theta / cos ^2 theta or not?
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    (Original post by Ed5)
    Must just be like this then. I wasn't really sure given you didn't mention the module, and 'simplify' can be quite open ended
    Thankyou for the advice anyway! It made me read ahead and did help
    I appreciated the advice!
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    (Original post by Desultory)
    Okay that makes sense thanks i worked it out now
    However, if there is a question where its tan^2 theta, can that equal sin^2 theta / cos ^2 theta or not?
    Yes that's also true but for a different reason:

    \displaystyle \tan^2 \theta = \left(\tan \theta\right)^2 = \left(\frac{\sin \theta}{\cos \theta}\right)^2 = \frac{\sin^2 \theta}{\cos^2 \theta}
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    (Original post by Notnek)
    Yes that's also true but for a different reason:

    \displaystyle \tan^2 \theta = \left(\tan \theta\right)^2 = \left(\frac{\sin \theta}{\cos \theta}\right)^2 = \frac{\sin^2 \theta}{\cos^2 \theta}
    Okay thanks now these questions seem easy!
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    (Original post by Desultory)
    Okay thanks now these questions seem easy!
    Getting good at C3/4 trigonometry is all about practice. Some students think they can get by if they just learn the identities but this doesn't work. You have to try as many different questions as you can to see how/where identities can be used and to pick up all the little tricks.

    When a student tells me that they hate C3 trig (common), I know that they probably haven't practiced enough
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    (Original post by Notnek)
    Getting good at C3/4 trigonometry is all about practice. Some students think they can get by if they just learn the identities but this doesn't work. You have to try as many different questions as you can to see how/where identities can be used and to pick up all the little tricks.

    When a student tells me that they hate C3 trig (common), I know that they probably haven't practiced enough
    haha i completely understand
    are you a teacher of maths?
    reccommend any good websites for tutors or even yourself?
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    (Original post by Desultory)
    haha i completely understand
    are you a teacher of maths?
    reccommend any good websites for tutors or even yourself?
    Yes I teach/tutor. If you google "maths tutor" then you'll find websites where you can find tutors near you.
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    (Original post by Notnek)
    Yes I teach/tutor. If you google "maths tutor" then you'll find websites where you can find tutors near you.
    ok thanks

    sec A - sec A * sin^2 A

    i did 1/cos A - 1/cos A * 1-cos^2A) but it doesnt really simplify
    have i done this wrong?
 
 
 
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