Afootball field is a 64-meter-wide, 100-meter-long rectangle.
what is the length of a diagonal of a football field to the nearest meter?

Use Pathagorean Theorem to solve (right triangle with the base being one of the side lengths and the height being the other side length.  a^2 + b^2 = c^2

64^2 + 100^2 = length of diagonal ^2

4096 + 10000 = 14096

The length of the diagonal is the square root of 14096 or 118.727 meters (rounded to the thousandths place).