What are Thomas Hariot's mathematical discoveries?

Answer 1

He created a mathematical formula for drawing lines of latitude on a chart so that a route with constant compass bearing would be a straight line on the map. "The sum of the angles of a spherical triangle is always larger than two right angles. The amount E by which it exceeds 180° is called the spherical excess. The 16th-century French mathematician Albert Girard showed that this excess determines the surface area of the triangle: the radius squared by the excess gives the area (in symbols, A=R²E)."

Resource Link: Unfortunately, I cannot add the link.