I tried that and I guess I don't understand what you mean. I made a triangle with the bezier tool and duped it 9 times then I started from the first dupe and rotated it 10 pixels but nothing happens. Do I start out with a white layer to put the triangle on?
10 degrees, not 10 pixels...
In slow motion:
You create a triangle path with a 5° angle (use guides and a little trig if you want the right angle easily):
Sunrays-1.png [ 18.67 KiB | Viewed 443 times ]
Then you make 8 copies, and using the Rotate tool in "transform path" mode (red arrow) you rotate each by the adequate multiple of 10°, making sure the rotation center is the center of the sun of course:
Sunrays-2.png [ 99.1 KiB | Viewed 443 times ]
Then you merge the visible paths, and get a selection from that merged path, that you can, for instance, bucket fill:
Sunrays-3.png [ 125.01 KiB | Viewed 443 times ]