Image 3-5: Early Dimensions of Home PlateThe home plate plays an essential guideline for the umpires in calling
strikes. This rule was soon abolished because the umpires were very
difficult in detecting the break of breaking balls. To help umpires and
pitchers in visualizing the strike zone, in 1900, a pentagonal home plate
was adapted. The new home plate was created by adding two isosceles
next to two sides of the original square shape.^11
According to Rule 2.02 in MLB’s handbook, “a home plate is made as a
17 inch square with two corners removed. The top edge is 17 inches, and
its two adjacent sides are 8.5 inches. The remaining two sides are defined
to be 12 inches each and they meet at a right angle”^12
But there’s something wrong with this figure: it is mathematically
impossible. Let's assume that we do not know the value of 12 inches and
let it be x. Then, let's connect the two points that are opposite the
sloping lines. This side has a length of 17 inches, and it divides the home
plate into an upper rectangle and a lower right triangle.