gistfile1.txt

kaiwren/rbmonk-class-example.rb 
class Rectangle
  def initialize(length, breadth)
    @length = length
    @breadth = breadth
  end
  def perimeter
    2 * (@length + @breadth)
  end
  def area
    @length * @breadth
  end
end
rectangle = Rectangle.new(5, 2)
puts rectangle.perimeter
puts rectangle.area

gistfile2.txt

#Area = ½ × b × h
#b = base
#h = vertical height 

class Triangle
  def initialize(base, height)
    @base = base
    @height = height
  end
  def area
    @base * @height /2
  end
end
triangle = Triangle.new(20, 10)
puts triangle.area

Going to try a circle next #Circle

Area = π × r2

Circumference = 2 × π × r

r = radius