Ortho mode makes it incredibly easy to draw or modify entities up and down, or left and right, but what if you have a typical angle other than 0, 90, 180, or 270 that needs to be used over and over?

This situation is where Polar Tracking comes into play.  Right-click on the Polar button at the bottom of your AutoCAD drawing window.  The Drafting settings dialogue box opens to the Polar Tracking tab.  Here is where  you can add more angles for the cursor to track other than the standard Ortho modes.  Set the increment angle to 45 and pick the OK button to close the dialogue box.  Depress the Polar button or use the F10 key to toggle this mode on.  Start the line command, pick a start point and then move your cursor until the Polar tracking information pops up at any 45 degree angle from the start point.

Don't forget that you can use more than one increment or create your own custom angle to use.