# Prove: Counterclockwise and positive determinant

• May 8th 2013, 11:21 PM
kotrfa
Prove: Counterclockwise and positive determinant
Hi,

I'm trying to prove fact, that positive determinant of e.g Attachment 28304 is counter-clockwise then and only then when the determinant is positive. In other words, that (u,v,p), where u=(a,d,g); v=(b,e,h), p=(c,f,i); is right-oriented set in R3.
I tried to play with matrix of rotation, but I wasn't successful.

Thank for ideas

P.S I'm not sure about the right English terminology, sorry for that
• May 9th 2013, 10:58 AM
HallsofIvy
Re: Prove: Counterclockwise and positive determinant
So you want to prove what is "counter-clockwise" if and only if the determinant is positive? You mean, I think, that the matrix maps a "right hand basis" into a right hand basis if and only if the determinant is positive.

One way to do that is use the fact that the signed volume of the tetradhedron bounded by vectors u, v, w is the determinant having those vectors as columns.