MedVision ad

exact value (2 Viewers)

fullonoob

fail engrish? unpossible!
Joined
Jul 19, 2008
Messages
465
Gender
Male
HSC
2010
how do i find the exact value of tan35, cant form the double angles atm
 

shaon0

...
Joined
Mar 26, 2008
Messages
2,029
Location
Guess
Gender
Male
HSC
2009
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

nigga
Joined
Sep 18, 2009
Messages
4,221
Gender
Male
HSC
2011
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

...
Joined
Mar 26, 2008
Messages
2,029
Location
Guess
Gender
Male
HSC
2009
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

nigga
Joined
Sep 18, 2009
Messages
4,221
Gender
Male
HSC
2011
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

...
Joined
Mar 26, 2008
Messages
2,029
Location
Guess
Gender
Male
HSC
2009
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

fail engrish? unpossible!
Joined
Jul 19, 2008
Messages
465
Gender
Male
HSC
2010
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
 
Last edited:

shaon0

...
Joined
Mar 26, 2008
Messages
2,029
Location
Guess
Gender
Male
HSC
2009
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

fail engrish? unpossible!
Joined
Jul 19, 2008
Messages
465
Gender
Male
HSC
2010
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:
 
Last edited:

shaon0

...
Joined
Mar 26, 2008
Messages
2,029
Location
Guess
Gender
Male
HSC
2009
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

fail engrish? unpossible!
Joined
Jul 19, 2008
Messages
465
Gender
Male
HSC
2010
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

fail engrish? unpossible!
Joined
Jul 19, 2008
Messages
465
Gender
Male
HSC
2010
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

...
Joined
Mar 26, 2008
Messages
2,029
Location
Guess
Gender
Male
HSC
2009
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
 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top