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Parametric Equations/Trigonometry [OCR June 2008 C4 Q9] Watch

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    Hi - I am struggling with part i), finding the angle at A and B. For B I was thinking y=0, but rearranging the parametric eqn for y gives theta = 0. I have no idea how to find A - all I can see is that it is a maximum point but I don't think that is relevant here. The mark scheme says the answer is A: 1/2 Pi and B: 2Pi. Any help would be much appreciated.

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    (Original post by MohammedPatel)
    Hi - I am struggling with part i), finding the angle at A and B. For B I was thinking y=0, but rearranging the parametric eqn for y gives theta = 0. I have no idea how to find A - all I can see is that it is a maximum point but I don't think that is relevant here. The mark scheme says the answer is A: 1/2 Pi and B: 2Pi. Any help would be much appreciated.

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    Yes, for B you need y = 0, so sin theta = 0 - there is more than one value of theta that makes sin theta = 0, it's just not just theta = 0...

    For A, you need to make y as maximum as possible, you know that sin theta is bounded between -1 and 1, so the maximum occurs at 1, so the maximum of 4sin theta occurs at y=4, at what value of theta does y=4 occur? You need only solve sin theta = 1.
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    Y is a maximum at A.
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    (Original post by Zacken)
    Yes, for B you need y = 0, so sin theta = 0 - there is more than one value of theta that makes sin theta = 0, it's just not just theta = 0...

    For A, you need to make y as maximum as possible, you know that sin theta is bounded between -1 and 1, so the maximum occurs at 1, so the maximum of 4sin theta occurs at y=4, at what value of theta does y=4 occur? You need only solve sin theta = 1.
    Thank you. This makes perfect sense
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    (Original post by Duck'sBackBRO)
    No offence bro, but do you have a life? Every thread I look at you're the first to reply...
    You're the loser who trolls a student forum so really... I mean, you gotta pretty damn retarded for you to do that.
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    (Original post by Zacken)
    You're the loser who trolls a student forum so really... I mean, you gotta pretty damn retarded for you to do that.
    You cannot even form sentences wtf is this
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    (Original post by Zacken)
    You're the loser who trolls a student forum so really... I mean, you gotta pretty damn retarded for you to do that.
    Also, I didn't mean to offend you or sound rude. It was an honest question... are there no ladies in Mauritius?
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    (Original post by Duck'sBackBRO)
    No offence bro, but do you have a life? Every thread I look at you're the first to reply...
    Sadly, I'd have to admit that I had this question in the back of mind...
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    (Original post by Moazer)
    Sadly, I'd have to admit that I had this question in the back of mind...
    Really? Is that why you created a dupe account...

    Such drivel is not worth Zacken's time.
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    (Original post by popo111)
    Really? Is that why you created a dupe account...

    Such drivel is not worth Zacken's time.
    and you are...?
 
 
 
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