C++ 计算并输出三角形的面积

题目描述

输入三角形的三条边长a、b、c，计算并输出三角形的面积。要求判断输入的三条边a、b、c三个数是否能构成三角，如果不能构成三角形，则输出提示信息告诉用户。

输入描述

输入三个数

输出描述

输出见样例

输入样例

3.5 4.6 5.7
1 2 3

输出样例

area=8.047
线段1.00,2.00,3.00不能构成三角形

#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

 int main(){
 	float  a, b, c; 
 	double s, area;
 	
 	cin >> a >> b >> c;
 
 	if (a + b <= c){
 		cout << "线段" << fixed << setprecision(2) << a << ","  << fixed << setprecision(2) << b << "," << fixed << setprecision(2)  << c << "不能构成三角形"<< endl;
	 }else if (a + c <= b){
	 	cout << "线段" << fixed << setprecision(2) << a << ","  << fixed << setprecision(2) << b << "," << fixed << setprecision(2)  << c << "不能构成三角形"<< endl;
	 }else if (b + c <= a){
	 	cout << "线段" << fixed << setprecision(2) << a << ","  << fixed << setprecision(2) << b << "," << fixed << setprecision(2)  << c << "不能构成三角形"<< endl;
	 }else {
	 	s = (a + b + c) * 0.5;
	 	area = sqrt(s * (s - a) * (s - b) * (s - c));
	 	
	 	cout << "area="<< fixed << setprecision(3) << area << endl;
	 }
 }