This one took a while to do...

If I take a sheet of 8.5"x11" paper and fold one corner to the opposite 11" side, what is the minimum possible length of the crease?

If I fold the opposite corners together, then I calculated the crease length as 8.5"*sqrt[1+(8.5"/11")^2], or about 10.74". My intuition says this should be the minimum, as the crease cuts across the paper with the shallowest possible angle.

define your shallowest angle

Wait. Is this a homework problem that you need to show your work for? :p

The angle the crease makes with the 11" side is closest to pi/2 rad. That is what I meant.

wait... the angle opposite the crease?
That's always pi/2.
As for the other two, they can't be pi/2
Try drawing a diagram and then label two sides x and y.
Then start labeling everything else in terms x, y and constants.
Solve for z, the crease, in terms of y.
That should be a huge hint...

I get a minimum length of 11.04

O_O im only 13, spare me! please have mercy!!!! lol jk i had these problems all the time in math class, let me see...