What are the angles of a home base?

Answer 1

There are three 90 degree angles. (Looking at home plate from a "pitcher's viewpoint), the wide "front" of home plate has 90 degree angles on both sides. The back point, e.g. "the heart of the plate," is a 90 degree angle. The two angles closest to the batter's back foot are both 135 degrees. This is because these angles are the sum of a 90 degree angle and a 45 degree angle. The back "triangle" of home plate is a 45-45-90 triangle.

Answer 2

90 degrees from 1st base line to 3rd base line.