import math

def area(base, height):
    '''(number,number) -> number
Return the area of a wirh given base and height.
>>>area(10,40)
200.0
'''
    return base * height / 2

def perimeter(side1, side2, side3):
    '''(number,number,number) -> number
Return the perimeter of the triangle with sides of
length side1,side2 and side3.

>>>perimeter(3,4,5)
12
>>>perimeter(10.5,6,9.3)
25.8
'''
    return (side1 + side2 + side3)


def semiperimeter(side1, side2, side3):
    return perimeter(side1, side2, side3) / 2


def area_hero(side1, side2, side3):

semi = semiperimeter(side1, side2, side3)
area = math.sqrt((semi * (semi - side1) * (semi - side2) * (semi - side3))
    return area