习题专题2-习题1 计算三角形面积

给定三点坐标计算三角形面积

有两个考点:

考点一:两点间距离公式

考点二:海伦公式

海伦公式:

a b c 为三边长

p=(a+b+c)/2

S=√p(p-a)(p-b)(p-c)

//考点一:两点间距离公式
//考点二:海伦公式
#include<math.h>
#include<stdio.h>
int main()
{
	double a1, a2, b1, b2, c1, c2;
	double x1 = 0;
	double x2 = 0;
	double y1 = 0;
	double y2 = 0;
	double x3 = 0;
	double y3 = 0;
	scanf("%lf %lf %lf %lf %lf %lf", &x1, &y1, &x2, &y2, &x3, &y3);

	double a = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));

	double b = sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
	
	double c = sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
	double p = 0;
	double s = 0;
	p = (a + b + c) / 2;
	s = sqrt(p * (p - a) * (p - b) * (p - c));
	printf("%.2lf",s );

	return 0;

}

运行结果: