<span>127.3 feet
This problem requires the use of pythagoras theorem. Ignore the face that it's a baseball diamond. All you're concerned with is that you have a square that's 90 feet per side and you want to know what the length of the diagonal. So you have a right triangle with 2 sides of 90 feet each and you want to know the length of the hypotenuse.
The formula is
C^2 = A^2 + B^2
Both A and B are 90, so plugging them into the formula gives
C^2 = 90^2 + 90^2 = 8100 + 8100 = 16200
So
C^2 = 16200
Take the square root of both sides
C = 127.2792
Round to the nearest tenth, giving
C = 127.3</span>
