"Analytic-Phi" for Math Nerds Trucker Hat

Geometry is one of the most ancient branches of mathematics. The Greeks developed a new method called Co-ordinate geometry or Analytical geometry; which today is also called “Cartesian” after the name of Rene Decartes (1596-1665). In order to transform from rectangular Cartesian coordinates (x,y,z) to spherical ones, and back, use the following Algebraic formulas: x = rho cos(theta)sin(phi), y = rho sin(theta)sin(phi), z = rho cos(phi), rho = ±sqrt(x2+y2+z2), theta = arctan(y/x), phi = arccos(z/sqrt[x2+y2+z2]). The value of phi is usually chosen in the interval between 0 and Pi, inclusive. The sign of rho is determined by which of the values of the arctangent function is chosen. Head hurt yet?? LOL! You must not be a math nerd!!