First we need to create
a circle, select the 'ellipse
tool'
from the main tools menu, click on the document
and as you drag the mouse and hold down the
shift key, constraining the circle.
Next we need to draw
a rectangle and modify it using the 'direct
selection tool' ,
to do this click on a paths corner point,
once selected the selected point will appear
a solid colour while all the other points
will be white. Then drag the point using the
mouse, once again if you hold the shift key
while dragging, it will constrain the path
points movement. Now select and drag the point
from the other side until we have a shape
something like this.
Now we need to position the shape to roughly
where we want it over the top of the circle.
A handy tip is to drag two illustrator guides
(one horizontal and one vertical) onto the
document unlock them and select the guides
and the circle and using the Illustrator
Align Tool align vertical center
and horizontal center.
Now select
the modified rectangle and using the 'rotate
tool'
click in the center of the circle while pressing
down the alt key. This will open a panel where
you can add the angle of rotation (fig1) then
click the copy button as seen below.
After clicking the copy
button press apple + D on a mac or Ctrl +
D on a PC, this will duplicate and continue
to rotate the shape, you should now have something
close to this.
Next select all the
elements and in the pathfinder panel click
on 'add to shape
area'
this will combine all the separate elements
into one.
from the main tools menu, click on the document
and as you drag the mouse and hold down the
shift key, constraining the circle.
,
to do this click on a paths corner point,
once selected the selected point will appear
a solid colour while all the other points
will be white. Then drag the point using the
mouse, once again if you hold the shift key
while dragging, it will constrain the path
points movement. Now select and drag the point
from the other side until we have a shape
something like this.
click in the center of the circle while pressing
down the alt key. This will open a panel where
you can add the angle of rotation (fig1) then
click the copy button as seen below. 
this will combine all the separate elements
into one.