"Dick Snyder" wrote in message
...
I'm not sure how to compute the bending radius. Maybe you can help me.
Here is what I know. The curved top piece of the bookcase will span a
width of 45". The highest point of the curve above a flat surface for a
reference point will be 8".

Don't compute it... just do it!

Place two nails 45 inches apart and place a mark 8" above the mid point.
Then take a thin flexible board, put it up against the nails and bend it up
to to the mid-point mark. Then trace the arc of the board with a pencil. You
can tinker with this basic approach a bit to get your ending and mid-points
just where you want them.

John