Start your protractor at 0 degrees. Make a mark at 1.8 degrees. Extend a line from the center of your circle, through that mark, to the edge of the circle.
Go back, and make a second mark, 1.8 degree above the first mark. Extend a line from the center point, through your 3.6 degree protractor mark, to the edge of the circle.
Repeat, ad naseum.