Although i get AC, but i want to know how the formula is derived..

2 PI * R + perimeter of polygon

The extra length is formed just a circle (radius = R).
i can image with just a few nails. but could you tell me the proof of this...

thanks..

if you got AC, it doesn't mean you solved it... It could  mean you copied someone's idea or even solution...

If you can't solve this kind of problems, how you gonna improve?

You can prove it by induction. Consider 1 nail, then 2, then 3, then k, then k+1.

Edited by author 05.04.2010 06:03

thanks..
i figured it out with a few number of nails..

just to clarify,, i didn't copy any other's idea or code...

just want to know any other mathematic proof,, that is all.

by using geometry,, merging angles of each nail,, you 'll get one circle (360 degree, radius = R).. that is my solution without induction.

Edited by author 05.04.2010 05:05

Edited by author 05.04.2010 05:12