I've got a board set at a 45 degree angle, back from a line. How much
(percentage) of the length of the board does it take up? To
conceptualize the issue, I drew a one inch line on paper with a ruler,
and rotated the ruler to a 45 degree angle, thinking that the one inch
mark on the ruler would be only 1/2 away from the starting point (along
the original path of the ruler), but it looks like it's about 90% along
the one inch span. What's the formula?

Dave