Question: My grandson comes to me for help with his school work. He is in 9th grade, but 10th grade math. The current problem is to take a normal 8 1/2 x 11 sheet of paper, take a corner and fold it to meet the opposite corner, and (without actually measuring) produce a formula to describe the result fold/crease. Having done this, the length of the crease seems to be equal to the length of the paper, but I tried on a different size sheet of paper and did not reach the same conclusion. help?

Hi Victoria,

I folded an 8.5 by 11 sheet of paper, photographed it and put some labels on the photo.

Let x inches be the distance from B to C and then the length of CA is 11 - x inches. ABC is a right triangle so write Pythagoras Theorem for this triangle. This will give you an equation you can solve for x.

Now that you have x can you see how to complete the problem?

Penny