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exact value (2 Viewers)

fullonoob

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how do i find the exact value of tan35, cant form the double angles atm
 

shaon0

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And how do you do that?
There's probably a shorter way than using tan(105/3) but find the expansion of tan3@ and then let @=x/3. You'll get x^3-3Kx^2-3x+K=0 where K=tan(105). And then just use the cubic formula lol. And sub in a hell lot of values.
 

mirakon

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There's probably a shorter way than using tan(105/3) but find the expansion of tan3@ and then let @=x/3. You'll get x^3-3Kx^2-3x+K=0 where K=tan(105). And then just use the cubic formula lol. And sub in a hell lot of values.
I doubt a hsc level student knows cubic formula. Is it even in the syllabus?
 

shaon0

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I doubt a hsc level student knows cubic formula. Is it even in the syllabus?
Nah, it isn't lol. I don't think they'll ask such crap questions. They're more likely to ask tan(15)=tan(45-30)
 

mirakon

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hmmm..... yes I agree. They'd probably just make you apply a single double-angle formula rather than such multi-step questions, espcially if the cubic is as inelegant as the above.
 

shaon0

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hmmm..... yes I agree. They'd probably just make you apply a single double-angle formula rather than such multi-step questions, espcially if the cubic is as inelegant as the above.
Yeah, only way there'd be a nice solution is if x E Q. And there's isn't one for this cubic.
 

fullonoob

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i still cant do it with the double angle result, i use the expansion of tan angles over 3 and i dont get the answer still..
lol dw making it over 3 is wrong method
how would you do it? solution please
 
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shaon0

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i still cant do it with the double angle result, i use the expansion of tan angles over 3 and i dont get the answer still..
lol dw making it over 3 is wrong method
how would you do it? solution please
If there's an exact value for tan(35), i'd like to hear it lol.
 

fullonoob

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LOLOL the question wasnt find exact values, dw i got it
was a show question xP

exploitable where do you get these epic animations, lags typing as well :eek:
 
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shaon0

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LOLOL the question wasnt find exact values, dw i got it
was a show question xP

exploitable where do you get these epic animations, lags typing as well :eek:
But you state: "find the exact value..."
 

fullonoob

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the question before it was find exact value
i was watching a movie while doing this so looked up and down and didnt read question :D
 

fullonoob

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i got a exact value question now
find exact value of tan (pi / 8)
using 1-cos2x / 1+cos2x = tan^2 x
i got the answer but i dont know how to get it into a simpler form, help ^^

root2 - 1 is the answer
i got root (3-2root 2)
yes i know its just a subbing in question, just dont know what to sub :p
 

shaon0

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i got a exact value question now
find exact value of tan (pi / 8)
using 1-cos2x / 1+cos2x = tan^2 x
i got the answer but i dont know how to get it into a simpler form, help ^^

root2 - 1 is the answer
i got root (3-2root 2)
yes i know its just a subbing in question, just dont know what to sub :p
tan(pi/8)=sqrt((2-sqrt(2))/(2+sqrt(2)))
=(2-sqrt(2))/sqrt(4-2) [Multiplying by:sqrt(2+sqrt(2))]
=sqrt(2)(sqrt(2)-1)/sqrt(2)
=sqrt(2)-1
 

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