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# C2 Trigonometry watch

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1. Solve for x, where: -181* < x < 180*

3cos^2x - 2sinx - 2 = 0
2. um i dont remember much but i'l try
3cos^2x= 2sinx+2
3(1-sin^2x)=2sinx+2
3-3sin^2x=2sinx+2
0= 3sin^2x + 2sinx-1
(3sinx-1)(sinx +1)
sinx=1/3 and sinx=-1
and find the sin values between the limits from there
3. (Original post by ShireenHeroin)
um i dont remember much but i'l try
3cos^2x= 2sinx+2
3(1-sin^2x)=2sinx+2
3-3sin^2x=2sinx+2
0= 3sin^2x + 2sinx-1
(3sinx-1)(sinx +1)
sinx=1/3 and sinx=-1
and find the sin values between the limits from there
the forum rules say youre not meant to do this...
youre meant to help someone answer a question, not give them a solution.
4. Right

Basically you need to get the 3cos^2x in terms of sin x using...

sin^2x + cos^2x = 1

Then what i do is then replace all the sin x's with u

3sin^2x + 2sinx-1 = 0

so this becomes

3u^2 + 2u - 1 = 0

then factorise
5. ther are forum rules
um sorry....i thought that would help
6. (Original post by ShireenHeroin)
ther are forum rules
um sorry....i thought that would help
Don't worry about it. Reading this could be a good idea though.
7. (Original post by ShireenHeroin)
ther are forum rules
um sorry....i thought that would help
dont worry he didnt exactly ask for help just to have a question solved.

OP - may i ask why someone is doing C2 work in the middle of the summer though?
8. (Original post by matt^)
dont worry he didnt exactly ask for help just to have a question solved.

OP - may i ask why someone is doing C2 work in the middle of the summer though?
they might want to retake
doesnt seem so farfetched does it
9. you cant retake until januay. is quite a long way off
10. (Original post by matt^)
OP - may i ask why someone is doing C2 work in the middle of the summer though?
I don't think doing some sort of work over the summer, how much or how little it may be, is particularly uncommon (especially for a TSR user ). People have plenty of reasons. Personally, I'm doing a little work out of interest (well, mostly out of interest - I can't honestly say that FP2 differential equations are that exciting).

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Updated: July 22, 2009
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