Okay thanks a lot everyone. Bernard
On 9/20/05, Kent Johnson <[EMAIL PROTECTED]> wrote: > Bernard Lebel wrote: > > Hello, > > > > I have this little math problem. I have this formula from wich I get a > > dot product between two vectors. > > > > cos(ß) = A.B / |A|.|B| = -0.0634 > > So this would give me radians, right? > > No, it's the cosine of ß, which has no units (a cosine is a ratio of two > lengths) > > > > > Then if I use > > > > math.degrees( -0.0634 ) > > > > This gives me a value of -3.6325524211294193. > > > > However I have a book in front of me who says I should get a value of > > 93.635 degrees. mmmmm > > > > Btw, in the book, the equation is written > > > > ß = cos-1(-0.0634) = 93.635, where -1 is actually an exponent. Maybe > > I'm just interpreting this wrong? > > The -1 means inverse. You have cos(ß) = -0.0634 - you want to find the angle > whose cosine is -0.0634, i.e. (inverse cosine)(-0.0634). Another name for > cos-1 is arccosine. In Python it is math.acos(): > >>> import math > >>> math.acos(-0.0634) > 1.6342388771557625 > >>> math.degrees(_) > 93.634990377223801 > > Kent > > > > > > > > Thanks > > Bernard > > _______________________________________________ > > Tutor maillist - Tutor@python.org > > http://mail.python.org/mailman/listinfo/tutor > > > > > > _______________________________________________ > Tutor maillist - Tutor@python.org > http://mail.python.org/mailman/listinfo/tutor > _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
