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# C3 trig help!! watch

1. Hi, my class recently started doing C3 and for some reason my teacher chose to begin with trig. He gave us some questions but I can't do any of them and I'm now in desperate need of help.
2. (Original post by Leandra_chk)
Hi, my class recently started doing C3 and for some reason my teacher chose to begin with trig. He gave us some questions but I can't do any of them and I'm now in desperate need of help.
For part a, use the first identity and divide it through by sin2

For part b, use your newly derived identity and leave cosec2 on one side, then square both sides to get an expression for cosec4 in terms of cot. Do the same to get cot4 in terms of cosec. Then just subtract cot4 from cosec4. Mess around with that expression and you should get there... or just difference of 2 squares.

For c, replace the left hand side with the alternative. Then you can express cosec2 in terms of cot2. Mess around with that and you should arrive to a quadratic which you can solve. I got values for cot to be 1/2 and -1. Since you know cot=1/tan, you can use this to solve for theta in the range between 90 and 180 degrees using general solutions or however else you solve them in Core 2.

I suppose you noted these down but in case you haven't: cosec=1/sin , sec=1/cos and cot=1/tan=cos/sin
3. (Original post by Leandra_chk)
Hi, my class recently started doing C3 and for some reason my teacher chose to begin with trig. He gave us some questions but I can't do any of them and I'm now in desperate need of help.
For b you should see it is the difference between two squares. Factorise it and use the result from a

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4. (Original post by gdunne42)
For b you should see it is the difference between two squares. Factorise it and use the result from a

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God dammit, why didn't I think of that. I knew there was something faster I just couldn't put my finger on it. -_-

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