enjoy_circle1.rb

#! /usr/bin/ruby

def area_circle(circle)
  circle.radius ** 2 * Math::PI
end

def dist_pos(pos1, pos2)
  diffx = pos1.x - pos2.x
  diffy = pos1.y - pos2.y
  Math::sqrt(diffx ** 2 + diffy ** 2)
end

def circle_include_pos(cir, pos)
  cir.radius > dist_pos(cir.center, pos)
end

# 座標を作って管理できるようにする
position = Struct.new("Position", :x, :y)

pos1 = position.new(0, 0)
puts pos1

# ２つの座標の距離
pos2 = position.new(2, 0)
puts "#{pos1}と#{pos2}の距離:#{dist_pos(pos1, pos2)}"

# 円を作って管理できるようにする
circle = Struct.new("Circle", :center, :radius)
cir1 = circle.new(position.new(0.0, 0.0), 1.0)

puts cir1

puts "面積#{area_circle(cir1)}"

puts circle_include_pos(cir1, pos1)
puts circle_include_pos(cir1, pos2)