If the radii have a common end point (or are joined (to join them you may Drag over the centre with the DirectSelection Tool (and Click the circle to deselect it)), and if they extend at least to the circle, you may simply select the radii and the circle and Pathfinder>Divide. That will give you two grouped partially circular paths with radii, like pieces of a pie, one with the angle, one with the complementary angle; you may need to restore the Stroke. If you ungroup or DirectSelect, you can colour either.
It may be possible to cheat in CS4 and use Live Paint Group or something.
Both radii are connected from the center to the circumference. After trying your approach, I selected both radii and the circle, selected Pathfinder>Divide and selected color (beside gradient), but the whole circle filled with the selected color which I don't want. What/Where is DirectSelect? Do I need to use it?
Both radii are connected from the center to the circumference. After trying your approach, I selected both radii and the circle, selected Pathfinder>Divide and selected color (beside gradient), but the whole circle filled with the selected color which I don't want.
If you look in the Layers palette/panel, you should find a Group with the two paths; you may click the desired path in the Layers palette or click elsewhere to deselect everything and then DirectSelect it (on the artboard) and then apply the colour.
What/Where is DirectSelect? Do I need to use it?
The Direct Selection Tool (white arrow) as opposed to the Selection Tool (black arrow). You need to use it to pick part of a path or group without using the Layers palette/panel. It is important to deselect everything to make it work.
Perhaps you want to use the Live paint Group as Jacob suggested as well .
1 select the circle and radii paths (The direct select tool is the arrow withe the white arrow head) If you hold the sghift key down while selecting objects you can select multiple objects like the elipse and the two radii.
2 Once those elements are selected click on the Live Paint Bucket in the tool Panel.
(this turns your art into a live paint group)
3 now with the Live Paint Bucket selected pick a fill color from the Swatches Panel
4 then hover the Live Paint Bucket over the area you want to fill with that color and click that will fill that area with the color
5. do the same with the other parts
6. if you want no color then use the no color swatch the white one with the red diagonl line through it.
thanks Wade, got it working.
Now the idea that you are cheating by using the Live Paint is just because jacob has always done it that way and as you can see sometimes using the Live Paint is a very direct way of going about things.
There are other ways like making it with the graph tool as a pie chart.
Both ways mentioned above are correct for a newer user Live Paint might offer advantages.
You should mark these both as answered since it comes up a lot and you have two most used methods described.
Jacob's would probably be more often than the Live Paint by users who have been working with Illustrator for many years but newer users would probably more likely to use the method I described.
I almost always go for the newer method.
This issue comes up a lot so if you mark it answer it would probably be helpful.