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Mathematics: Post your doubts here!

angelicsuccubus

angelicsuccubus

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H

hm12

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Nouman Shafique said:
cos4@ - 4cos2@
2cos^2 2@ -1 - 4cos2@
2(cos2@)^2 - 1 - 4(cos2@)
2(2cos^2 @ -1)^2 - 1 - 4(2cos^2 @ - 1)
solve it ahead u wud get the anwer, i have done the tricky part
Click to expand...
i have already done till here but still when i solve it further the answer is not coming can you please show all steps? i will be really appreciate your help :)
 
angelicsuccubus

angelicsuccubus

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hm12 said:
i opened your link thinking the same but the one i am asking is different because in this you have to prove it equal to sin^4 theeta not cos^4 theeta
Click to expand...
oh sorry.. Im really tired so I didn't see that but any way it's the same thing cause cos2A=1-2sin^2A and cos4A=1-2sin^(2)(2A) .. and you follow the same method kay?

Now Imma go sleep for a couple hours.. if you get stuck on something like this again .. try www.wolframalpha.com
 
Mobeen

Mobeen

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angelicsuccubus said:
forget it and go sleep? I can't even think straight anymore plus I suck at p3 =[ .. maybe you could find somethin on youtube?
Click to expand...
other than vectors im pretty much good .. so yeah forget it ! ...
found some funny videos on youtube . :p or were you talking about vectors :p
 
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hm12

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Nouman Shafique said:
cos4@ - 4cos2@
2cos^2 2@ -1 - 4cos2@
2(cos2@)^2 - 1 - 4(cos2@)
2(2cos^2 @ -1)^2 - 1 - 4(2cos^2 @ - 1)
solve it ahead u wud get the anwer, i have done the tricky part
Click to expand...
okay i finally managed it was just a plus minus mistake but this question drove me mad i mean its working is too long :/
 
angelicsuccubus

angelicsuccubus

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hm12 said:
okay i finally managed it was just a plus minus mistake but this question drove me mad i mean its working is too long :/
Click to expand...
I just answered it.. its not that long if you switched everything to sin at the beginning.. and I suck at trig - don't forget they give you practically everything in the data booklet.
 
Mobeen

Mobeen

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angelicsuccubus said:
lol i meant vectors.. but before you sleep.. can you please answer q7b and 8i here?
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_32.pdf
please and thankyou
Click to expand...
dont know the argand diagrams sorry !
and 8i is just binomial of the partial fraction..
partial fraction is = -2/(1+x) + (x+4)/(2+x^2)
it would be:
-2(1+x)^-1 + (x+4)(2)^-1(1+(x^2)/2)
binomial of the first fraction is easy . and binomial of the second is easy too and multiply it by (x+4)(2^-1)
 
RGBM211

RGBM211

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x=sin4tetha +2sin2tetha and y=cos4tetha-2cos2tetha

where -pie/6<tetha<pie/6 show that dy/dx= -tantetha

can someone solve it
 
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hassam

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well i didnot understand the validity of binomial expansion part....cn smbody give ma quick review of it
 
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