calculate points on the circumference of a circle

circle_calc.rb

# -*- coding: utf-8 -*-
# A simple class to calculate approximately any point on a circle defined by the radius
class Circle
  def initialize(radius)             # Might be actually the diameter; just whipping up some quick code
    @radius = radius
  end

  def [](theta)
    #                     π
    # You must multiply  ---  to convert theta from degrees to radians
    #                    180
    t = theta * Math::PI / 180.0
    x = Math.sin(t) * @radius
    y = Math.cos(t) * @radius
    [x, y]
  end
end

# Create a circle with a radius of 50 units
c = Circle.new(50)
# Create a list of evenly spread angles to query. This should get the points on the circle at the angles
# 90, 180, 270, and 360
max = 4
angles = (1..max).collect {|d| 360 * (d.to_f / max)}
# Now to print our info to the user                                                                                                          
puts "For a circle with a radius of 50:"
angles.each do |a|
  pt = c[a]
  puts "  • The point at #{a}° on the circle is approximately (#{pt[0]}, #{pt[1]})"
end