figuras.py

class Triangle(object):
    classType = "triangle"
    def __init__(self, side1, side2, side3):
        self.side1 = side1
        self.side2 = side2
        self.side3 = side3
        
    def area(self):
        return "The area of this %s is:       %s" % (self.classType,self.side1 * self.side2 / 2)
    
    def perimeter(self):
        return "The perimeter of this %s is:  %s" % (self.classType,self.side1 + self.side2 + self.side3)
        
class Circle(object):
    classType = "circle"
    def __init__(self, radius):
        self.radius = radius
        
    def area(self):
        return "The area of this %s is:         %s" % (self.classType,3.1416*self.radius**2)
        
    def perimeter(self):
        return "The perimeter of this %s is:    %s" % (self.classType,3.1416*self.radius*2)
        
class Square(object):
    classType = "square"
    def __init__(self, side):
        self.side = side
        
    def area(self):
        return "The area of this %s is:         %s" % (self.classType,self.side**2)
        
    def perimeter(self):
        return "The perimeter of this %s is:    %s" % (self.classType,self.side*4)     
        
        
tri = Triangle(5,4,3)
print(tri.area())
print(tri.perimeter())

circ = Circle(5)
print(circ.area())
print(circ.perimeter())

sq  = Square(3)
print(sq.area())
print(sq.perimeter())