The first thing you need to know, is ARC needs three sets of coordinates to make it work. The first two sets ( a set has two numbers like this: 100,150 or +100+150) determines where it begins and ends. Not like the LINE, but instead like the RECTANGLE. The ARC rotates within the RECTANGLE. The beginning set (1st numers or coordinates ) measure where the top left corner is located. The second set determine the location of the bottom right corner. Remember, the ARC is working within a SQUARE or RECTANGLE.

The last set determines the amount of rotation which will occur. The first number in the set begins the rotation, the second number ends it. If you look below, you will see a graph of rotation that might help.

This is another bit of important information you need to know about the ARC's rotation: the first number, which begins the rotation, moves only in a clockwise direction around the graph. Think of it as a clock. Let's say the third set are 3:00, 6:00. 3:00 begins the rotation so that means there will be three hours to 6;00. Now, let's switch them. 6:00, 3;00. There are now nine hours from 6:00 to 3:00. Below is an example.

The blank gif is 300x400. I created the rectangle to enable you to see the Arc's rotation working within it. Rectangle: first set of numbers to determine the top left corner. 20,20. ( 20 across and 20 down). The second set determine the bottom right corner. 280,380 (280 across and 380 down). Now, for the third and last set of numbers. 360 ( you can go no higher) and 90. 360,90. The 360 begins the rotation and ends at 90. I then switched the last two numbers around. 90,360. The results below.

As you can see, the 90 now begins the rotation and moves all the way around to 360 making the ARC longer.

I wondered if it was possible to make a complete rotation, all the way around. I tried 90,90. Nothing happened. It could be because there is no where for it to travel to. I thought maybe 90,89 would work. It would leave one degree of rotation incomplete. Not good. I can see how that would drive some a little nutty.

I checked the graph again, and noticd that 360 and 0 share the same spot on it. The 0 begins the graph and 360, ends it. Makes since that 0,360 will make a complete rotation. See below.