# curvature of planar curves

• May 19th 2010, 06:31 AM
Iggy
curvature of planar curves
Ok, so, i have a serious problem and i need help, since english is not my mother language i'm not sure if this is the right name of the problem..

i have function in implicit shape y^2 = x^2 * ((4+x)/(4-x))

and for the curvature there is formula http://img203.imageshack.us/img203/727/formulaq.jpg

and i don't understand how to get to those parameters

help pls
• May 19th 2010, 08:49 AM
HallsofIvy
I guess then the question is "what is F". That is, what does the function F represent in that formula? Are the subscripts indices or derivatives? And if they are derivatives, what do F' and F'' mean?
• May 19th 2010, 09:13 AM
Iggy
Quote:

Originally Posted by HallsofIvy
I guess then the question is "what is F". That is, what does the function F represent in that formula? Are the subscripts indices or derivatives? And if they are derivatives, what do F' and F'' mean?

well that is what i wonder too..I got that formula from Bronstein's handbook of mathematics, as a formula for curvature, but i don't really understand anything about it =(((
• May 19th 2010, 09:24 AM
Iggy
I found another formula
http://img24.imageshack.us/img24/2314/formula2n.jpg

But this doesn't help me much either cause i really don't understand this stuff..
• May 19th 2010, 10:47 AM
Iggy
anyone??

anything??