Differential of sin^2(x)?

OSB · 24 Sep 2007 at 17:31

I can never remember how to do this! Could someone show me how please. To clarify that is how do i differentiate sine squared x?

Thanks,

OSB

Gaverick · 24 Sep 2007 at 17:34

You've been posting your homework on here all day!

Monkey Puzzle · 24 Sep 2007 at 17:35

Your "I've done most of them, I just need help with a few" remark becomes less believable with every new thread.

gord · 24 Sep 2007 at 17:37

Ah, you tried to trick me eh.. the old.. "i can never remember this" ploy.. im fairly sure google and some textbooks will be your friend.

OSB · 24 Sep 2007 at 17:41

Don't have any books and i've looked on google!!! I could type up all the questions i HAVE done to show you i am working, but tbh i cba!!! Com'on what productive things have you people done all day then!!!

sniffy · 24 Sep 2007 at 17:43

Been to college and done my own work

OT: Playing TF2 tonight gord?

Inquisitor · 24 Sep 2007 at 17:43

Edit: ignore me!

p4radox · 24 Sep 2007 at 17:46

Try using the trig identity cos(2x) = 1 - 2sin^2(x)

V4NT0M · 24 Sep 2007 at 17:50

lol refer to my other post... In the other thread.

Psiko · 24 Sep 2007 at 17:52

Do you know the chain rule? If h(x) = f(g(x)), then h'(x) = g'(x) f'(g(x)). Now, if h(x) = sin^2 (x), can you work out f(x) and g(x), and therefore h'(x) = ...

[TR]SweetSpotOz · 24 Sep 2007 at 17:53

OSB said:
I can never remember how to do this! Could someone show me how please. To clarify that is how do i differentiate sine squared x?

Thanks,

OSB

(sinx)^2

Chain rule will give you:
2(sinx)*(cosx) (differentiate outer function first multiply by the derivative of the inner funtion).

So 2sinxcosx, which if I'm not mistaken is sin2x.

What course are you about to do at uni?

OSB · 24 Sep 2007 at 18:10

Thank you, thats the badger i was looking for! The question was giving me a method in a notation i couldn't uderstand but now it makes sense! I know i shold know how to do that but i forgot! A good 3 months having done NO thinking whatsoever!!! I'm about to start a natural sciences couse at cambridge, maths physics chemistry and geology! eek!

[TR]SweetSpotOz · 24 Sep 2007 at 18:18

You are doing NatSci at Cambridge and you don't know the chain rule? What college are you staying in?

Good luck!!!

neil3k · 24 Sep 2007 at 18:19

OSB said:
Don't have any books and i've looked on google!!! I could type up all the questions i HAVE done to show you i am working, but tbh i cba!!! Com'on what productive things have you people done all day then!!!

Been to work all day you might want to try it,

Zom · 24 Sep 2007 at 18:21

http://www.calc101.com/webMathematica/derivatives.jsp