In the official rules for baseball, home plate is defined as an irregular pentagon with three right angles. Two sides of the plate are set at 8.5″, two angled sides at 12″, and one flat side at 17″, which faces the pitcher. The only problem with this shape is that it is mathematically impossible.
As the Major-General could tell you, the Pythagorean theorem states that the squares of the sides of a right triangle must add up to the square of the hypotenuse. In this case, however, 12 squared added to 12 squared equals 288, while the square of 17 is 289. To fix this, most home plates either shorten the front side to 16.9″ or enlarge the back angle to more than 90°. Not a single baseball game has ever been played with a regulation home plate, in spite of the fact that “home plate” is used to define “strike zone,” “out,” “run,” etc.
Just something to keep in mind in case you ever find yourself in the bottom of the ninth with the score against you. “Excuse me, umpire, I’d like to dispute the validity of the other team’s runs. See, none of them actually crossed home plate…”