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

1. 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.

2. (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.

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.
3. Y is a maximum at A.
4. (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
5. (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.
6. (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
7. (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?
8. (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...
9. (Original post by Moazer)
Really? Is that why you created a dupe account...

Such drivel is not worth Zacken's time.
10. (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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