Add Yahoo as a preferred source to see more of our stories on Google. A high school teacher didn't expect a solution when she set a 2,000-year-old Pythagorean Theorem problem in front of her students.

Two years ago, a couple of high school classmates each composed a mathematical marvel, a trigonometric proof of the Pythagorean theorem. Now, they’re unveiling 10 more. For over 2,000 years, such ...