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    • Thread Starter

    1. cosec? + 2cosec 2? / sec? = cot?/2

    2. 1+tanatan2a = sec2a

    3. 2sin? sin2?/ cos? + cos3? = tan2?tan?

    4. sin3?/sin? - cos3?/cos? = 2

    5. cos3?/cos? + sin3?/sin? = 4cos2?

    6. (tan?/2 + cot ?/2) / (cot?/2 - tan?/2)

    7. sin3?/cos? + cos3?/ sin? = 2cot2?

    I was working on my assignment questions and I got stuck in those.. can you please help me !!

    Thank you
    • PS Helper

    PS Helper
    The format of these is all the same -- you just need to apply identities. My advice is to convert everything into sines and cosines, and work from the more complicated-looking side to the more simple-looking side. I'm not going to give you the solutions to these problems, but good tricks to look out for are:

    (i) Getting rid of 2\thetas by using double-angle identities (unless they appear on both sides, in which case leave them there)
    (ii) Getting rid of 3\thetas by writing 3\theta = 2\theta + \theta and using the angle-addition formulae
    (iii) Doing (i) and (ii) in reverse (e.g. writing \sin \theta \cos \theta in terms of \sin 2\theta)
    (iv) Looking out for things in the form \sin^2 A + \cos^2 A
    • Thread Starter

    I do try doing these methods but it just doesn't work for me !;(
    • PS Helper

    PS Helper
    (Original post by Abady.f)
    I do try doing these methods but it just doesn't work for me !;(
    Well show your working! No-one here's going to do 7 questions for you.
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