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#1
can anyone help me prove that

tan2x = (2tanx) / (1-[tanx ]^2)

??
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#4
just thought it might be a slightly higher class of homework-mooch than the other stuff we get on here, like "whats 5+2" or "what does freedom mean to me?"
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#5
Quote by McTodd
can anyone help me prove that

tan2x = (2tanx) / (1-[tanx ]^2)

??

Proofs are feckin' terrible. You know how to do them, right? Make what's on the right look like what's on the left and list the rules you've used every step.

[IN PHIL WE TRUST]


Quote by Trowzaa
I only play bots. Bots never abandon me. (´・ω・`)

#6
tan(A+B)=(tanA+tanB) / (1-tanAtanB)

Hence
tan 2A = (tanA+tanA) / (1 - tanAtanA)

=(2tanA) / (1-(tanA)^2)
Sunderland AFC
#7
i could have done that a year ago, but not now
I sat next to a nun on the bus once, she said hi

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#8
Quote by hendo123456789
tan(A+B)=(tanA+tanB) / (1-tanAtanB)

Hence
tan 2A = (tanA+tanA) / (1 - tanAtanA)

=(2tanA) / (1-(tanA)^2)

sorry, i'm not allowed to use tan identities, only sin and cos
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#9
Quote by McTodd
sorry, i'm not allowed to use tan identities, only sin and cos

I'm three years removed from those, but aren't the tangent identities derived from the sine and cosine ones?

[IN PHIL WE TRUST]


Quote by Trowzaa
I only play bots. Bots never abandon me. (´・ω・`)

#11
Quote by SteveHouse
I'm three years removed from those, but aren't the tangent identities derived from the sine and cosine ones?

yeah, and i don't know how to do it!
*cries like a prepubescent blonde girl*
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#12
Quote by McTodd
sorry, i'm not allowed to use tan identities, only sin and cos

You don't like tan? Racist.
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#14
I expected Maths combined with bungee jumping or something.

ಠ_ಠ

wat

#15
start with tan2A = sin2A / Cos2A

i cant quite remember the rest from there.

Even though i do have an exam involving this tomorrow!!!
Sunderland AFC
#16
Quote by Jaymz_515
I expected Maths combined with bungee jumping or something.


[IN PHIL WE TRUST]


Quote by Trowzaa
I only play bots. Bots never abandon me. (´・ω・`)

#17
Quote by monkeysintheday
are t-a-n all separate variables?



Hilarious!
¯|(°_o)/¯
#18
Quote by Jaymz_515
I expected Maths combined with bungee jumping or something.

no
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#21
Can you use it in a sentence?
Let's not bicker and argue about who killed who...
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YOU WILL NOT ENJOY THIS......
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#22
Quote by McTodd
no


Well yeah I noticed after I came in. Thanks for reiterating it though.

ಠ_ಠ

wat

#23
Quote by 0RI0N
Can you use it in a sentence?

"the tan2x F'd you in the A"
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#24
Quote by monkeysintheday
are t-a-n all separate variables?






I can't tell if that's epic win or epic fail.
#25
think i got it - thread needs closure!

tan2x = sin2x / cos2x
= 2sinxcosx / cosx^2 - sinx^2
then divide numerator and denominator by cosx^2 to get
= 2tanx / 1 - tanx^2

fulking hellburgers!
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#28
Quote by Craigo
That.

C3 tomorrow?

I don't like C3.
C4 is easier. Although the comprehension paper is a load of balls. I don't wanna do the exam tomorrow.
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#29
Quote by monkeysintheday
are t-a-n all separate variables?


After being disapointed by the misleading title... this saved the thread

EDIT: How's everyone feeling about C3? Any other further maths students here?
don't let the forest grow over the path you came here by
#30
THe answer is 23,,,,,,,,,,,,,,,,or is maybe it's not..........I probably should not listen to me because I'M A LIAR, A LIAR
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#31
seeing as im not great at math ill give it a go
can i set x=1?

tan2x = (2tanx) / (1-[tanx ]^2)
tan2(1) = (2tan(1) / (1-[tan(1) ]^2)
tan2=tan2/tan1
tan2= tan2

??

that was just rearranging, im not up on my trig.
#33
Quote by PinkFloyd73
seeing as im not great at math ill give it a go
can i set x=1?

tan2x = (2tanx) / (1-[tanx ]^2)
tan2(1) = (2tan(1) / (1-[tan(1) ]^2)
tan2=tan2/tan1
tan2= tan2

??

that was just rearranging, im not up on my trig.


You're going about it wrong, you take one side and reaarange it until it says the other side.
don't let the forest grow over the path you came here by
#34
C3 sucks balls. i think i'll just shred instead.
*shreds*
*neglects C3*
*gets F*
*works in mcdonalds rest of life*
*dies early of heart disease*
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#35
Math Thread?

And my condolences, McTodd. I hope your next life is better.
#36
Quote by OCDeity
Math Thread?

And my condolences, McTodd. I hope your next life is better.

the worst part is, i can't even shred. might as well kill myself now and get it over with.
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#37
Seriously, what the **** are you talking about?
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#40
Quote by McTodd
"the tan2x F'd me in the A"


Fixed.
Let's not bicker and argue about who killed who...
Quote by Necrophagist777
I'm ORION, LORD OF EVIL, give me your soul and breathe in my darkness.

YOU WILL NOT ENJOY THIS......
╭∩╮( º.º )╭∩╮
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