class Triangle:
    def __init__(self,a,b,c):
        self.cotes = [a, b, c]
        self.cotes.sort()

    def rect(self):
        return self.cotes[2]**2 == self.cotes[0]**2 + self.cotes[1]**2

    def aire(self):
        if self.rect():
            return self.cotes[0] * self.cotes[1] / 2
        else:
            p = (self.cotes[0] + self.cotes[1] + self.cotes[2])/2
            return (p*(p-self.cotes[0])*(p-self.cotes[1])*(p-self.cotes[2]))**0.5