Can someone point me in the right directon

1. Aug 2, 2007

gona

the problem is to intigrate cot$$^{2}$$x

now i kow that cot$$^{2}$$x = $$\frac{cos^{2}x}{sin^{2}x}$$

now iv tryed various substitutions like usig the power reducton forumulas...
and then using double angle substiutions but nothin seems to work for me

so i was wondering if somone could just tell me where to start so i can
finish this question.... been trying to figure this out for like a hour now

Last edited: Aug 2, 2007
2. Aug 2, 2007

HallsofIvy

Staff Emeritus
Use the identities 1+ cot2(x)= csc2(x) so that cot2(x)= csc2(x)- 1. Since you know that the derivative of cot(x) is csc2(x), that should be easy.

3. Aug 2, 2007

gona

Wow that was suprisingly simple thank alot yea i didnt know about that identity that was the first time iv used it. Thnx alot great help

4. Aug 2, 2007

Kurdt

Staff Emeritus
There are many pages that list trig identities. Whenever I work with trig functions I always just open a page and have a look at how the functions in the question are related. There are loads of pages, but I do like wikipedias as it has a list of the 6 trig functions in terms of the others which is very handy for some integration questions when trig substitution is needed.

http://en.wikipedia.org/wiki/Trigonometric_identity

5. Aug 2, 2007

gona

Wow very nice im gonna bookmark this page right away thnx again!