[Tutor] Calculating Deflection angles

[nitin chandra]

Hello Every One,

I create a list of coordinates of 2 lines.
X11,Y11 & X12,Y12 as starting and ending of one line.
X21,Y21 & X22, Y22 as starting and ending of the 2nd line.

Now is there any way to calculate the deflection angle between the two
lines? Will any modules be required other than Python 2.3 (on Linux)?

and

How will it be done?

TIA,

Nitin