Arthur D. answered 03/20/20
Mathematics Tutor With a Master's Degree In Mathematics
Another solution is to use the Law of Cosines
Draw a diagram
The distance from the pitcher's mound to home plate is 60.5 feet.
Draw this segment. It bisects the 90° angle at home plate. (two 45° angles)
The distance from home plate to first base is 90 feet.
Draw a segment from the pitcher's mound to first base. This is the distance that you want.
Use the Law of Cosines.
Call the distance from the pitcher's mound to first base "x".
x^2=60.5^2+90^2-2(60.5)(90)cos45°
x^2=3660.25+8100-10,890(0.70710678)
x^2=11,760.25-7700.392
x^2=4059.858
take the square root of both sides
x=63.717015
x=63.7 feet