Are you wanting to figure out a way to determine how to rotate the map so that North is always up?
I will demonstrate on 9.3.1
There is a small formula you can use to calculate the amount of rotation needed:
get the InvTan of (YDifference / XDifference)
For instance, if I draw a line at an angle:
[ATTACH]4808[/ATTACH]
Start an edit session to get the X,Y coordinates of the corners/ends:
Feature Selected in Edit session:[ATTACH]4809[/ATTACH]
Hover over a vertex, right click and select Properties to open sketch properties window: [ATTACH]4810[/ATTACH]
Note the x,y values and get their difference: X1 - X2 and Y1 - Y2
Xdiff = 2744882.428 - 1613945.359 = 1130937.069
Ydiff = 6677341.207 - 6448747.544 = 228593.663
Press Windows Key + R and type in "calc" without the quotes and hit enter to open the calculator:
Result shown is from InvTan (228593.663 / 1130937.069)
In calculator, do the division calculation first, which should, in this case give you: 0.20212765967794093059301781538828
With that result in the window, place a checkmark beside Inv, and press the Tan button:
[ATTACH]4811[/ATTACH]
Result: 11.42710159964098606467054232324
or
rotate dataframe 11.427 degrees, or -348.573 degrees
[ATTACH]4812[/ATTACH]