题解 | 三角形面积

import math

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

class Triangle:
    def __init__(self, a, b, c):
        self.a = a
        self.b = b
        self.c = c
        self.A = b.y - a.y
        self.B = a.x - b.x
        self.C = b.x * a.y - a.x * b.y

def get_diecrt(T):
    if T.a.x == T.b.x:  
        return abs(T.c.x - T.a.x)
    else:
        return abs(T.A * T.c.x + T.B * T.c.y + T.C)/(math.sqrt(T.A ** 2 + T.B ** 2))

def get_double(T):
    return math.sqrt(T.A ** 2 + T.B ** 2)

def get_area(T):
    # TODO: 计算三角形T的面积
    diecrt_distence = get_diecrt(T)
    double_distence = get_double(T)
    return diecrt_distence * double_distence / 2 
    pass














































































































































































































































































































































def main():
    x, y = map(int, input().split())
    a = Point(x, y)
    
    x, y = map(int, input().split())
    b = Point(x, y)
    
    x, y = map(int, input().split())
    c = Point(x, y)
    
    T = Triangle(a, b, c)
    print("{:.2f}".format(get_area(T)))

if __name__ == "__main__":
    main()