#1
Might as well give this a shot. Anyone good with Calc? I have 2 problems I'm not sure how to do in a big list.

lim cost(theta)-1 / lim sin(theta)
theta -> 0

right off the bat you can see it will be 0/0, which makes me think theres more to it, the whole list of problems is somewhat complex, then this.


annnnd:

lim sin^2 3t / t^2 (variable t, not theta)
t->0

I'm stumped, any advice would be great.
#2
Sorry dude. I did this stuff a long time ago and i forget the different rules applied to theta.

All i can see is that the negative 1 will invert the divide to make it a multiply and the ^2 can be factored out somehow. I really don't know what im on about...
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#4
as far as i can tell both are undefined but i'm flying by the seat of my pants here so don't take my word for it. you could also try l'Hospital's Rule but i don't remember if it applys here. i took ap calc my junior year in high school so it's been a while. sorry i couldn't be more help.
#6
Well, at least it's reassuring others forget easily, as I can't remember anything from pre-calc 2 years ago, hah.
#7
L'Hospital's rule is right because if you plug in 0 they both reduce to 0/0 (also works when it reduces to infinity/infinity). Take the derivative of of both the numerator and the denominator (separately) and then try it again. For the first one, after taking the derivatives it is -sin(theta)/cos(theta) = -tan(theta). -tan(0) = 0 so the answer to the first one is 0. Do the same thing for the second function, except you have to repeat the process twice. sin^2(3t)/t^2 --> 6sin3tcos3t/2t --> ( -18sin^2(3t) + 18cos^2(3t) ) / 2, plug in 0 for t and you get 9. Hope that helps
#8
Well im not soo gud at it either dude...but for da first one da answer's -1...lol...im not really sure tho...if u want da workin and stuff...here it is...i think its wrong but hey i tried...lol...

lim cos(theta) - 1
theta -> 0 ------------------
sin(theta)

lim cos^2(theta) - 1^2
theta -> 0 ------------------------- *squaring both sides
sin^2(theta)

lim cos^2(theta) - 1
theta -> 0 ---------------------
sin^2(theta)

lim - sin^2(theta)
theta -> 0 ----------------- *Trig identity cos^2(theta) + sin^2(theta) = 1
sin^2(theta)

lim -1
theta -> 0


I dunno bout da second one...i forgot da identity for dat one and i dont hav my AP Calc book...lol...sorry...but if u hav anymore questions, feel free to ask and imma try to help....
#9
OK da last one sucked...it wrapped automatically...and i dont think its very comprehendible so im tryna correct it now...if u still cant understand...pls lemme knw and i'll attach it or sumthin...
#10
lim cos(theta)-         1 
                  lim  _________
                     sin(theta)

theta -> 0 



Is that supposed to be CosT Theta???
and Theta tends to 0 it is not 0

Is his Diffretiation cos If it is I can do it

Is thats how its supposed to be Laid out


then the Answer is


Theta 1
_____ - _____
1 Theta


Theta^2 - 1
___________
Theta


Answer is

Theta - 1
Last edited by dazzler16 at Feb 28, 2007,
#12
Thanks so much for the replies everyone! Everything posted helps alot, I should be good to go now, thanks again