#Calculate the area of a user defined circle or triangle

option = 0

while option != 3:
     print "1. Find the area of a triangle."
     print "2. Find the area of a circle."
     print "3. Exit program."
     print "--------------------------------"

     option = int(raw_input("Select an option: "))

     #Area of a triangle
     if option == 1:
          base = float(raw_input("Enter the length of the base: "))
          height = float(raw_input("Enter the height of the triangle: "))

          #Check for valid input
          if (base < 0) or (height < 0):
              print "You must enter non-negative values."
          else:
              area = .5 * base * height
              print "The area of the triangle is " + str(area) + "."

     #Area of a circle         
     elif option == 2:
          radius = float(raw_input("Enter the radius of the circle: "))

          #Check for valid input
          if (radius < 0):
              print "You must enter a non-negative value."
          else:
              area = 3.14 * radius**2
              print "The area of the circle is " + str(area) + "."
     elif option == 3:
          print "Exiting Program"
              
     #Invalid option
     else:
         print "You did not enter a valid option."