根据输入的三角形的三条边a、b、c，计算并输出面积和周长。注意：在一个三角形中， 任意两边之和大于第三边。三角形面积计算公式：area=s(s−a)(s−b)(s−c)，其中s=(a+b+c)/2。 点击复制后，将打开C知道体验页

a = float(input())
b = float(input())
c = float(input())
if a+b > c and a+c > b and b+c > a:
    s = (a+b+c)/2
    area = (s*(s-a)*(s-b)*(s-c))**0.5
    perimeter = a+b+c
    print("area = {:.2f}; perimeter = {:.2f}".format(area, perimeter))
else:
    print("These sides do not correspond to a valid triangle")

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        double a = in.nextDouble();
        double b = in.nextDouble();
        double c = in.nextDouble();
        if (a+b > c && a+c > b && b+c > a) {
            double s = (a+b+c)/2;
            double area = Math.sqrt(s*(s-a)*(s-b)*(s-c));
            double perimeter = a+b+c;
            System.out.printf("area = %.2f; perimeter = %.2f", area, perimeter);
        } else {
            System.out.println("These sides do not correspond to a valid triangle");
        }
    }
}

#include <iostream>
#include <cmath>
using namespace std;
int main() {
    double a, b, c;
    cin >> a >> b >> c;
    if (a+b > c && a+c > b && b+c > a) {
        double s = (a+b+c)/2;
        double area = sqrt(s*(s-a)*(s-b)*(s-c));
        double perimeter = a+b+c;
        printf("area = %.2f; perimeter = %.2f", area, perimeter);
    } else {
        cout << "These sides do not correspond to a valid triangle";
    }
    return 0;
}

a, b, c = map(float, input().split())
if a+b > c and a+c > b and b+c > a:
    s = (a+b+c)/2
    area = (s*(s-a)*(s-b)*(s-c))**0.5
    perimeter = a+b+c
    print("area = {:.2f}; perimeter = {:.2f}".format(area, perimeter))
else:
    print("These sides do not correspond to a valid triangle")

#include <iostream>
#include <cmath>
using namespace std;
int main() {
    double a, b, c;
    cin >> a >> b >> c;
    if (a+b > c && a+c > b && b+c > a) {
        double s = (a+b+c)/2;
        double area = sqrt(s*(s-a)*(s-b)*(s-c));
        double perimeter = a+b+c;
        printf("area = %.2f; perimeter = %.2f", area, perimeter);
    } else {
        cout << "These sides do not correspond to a valid triangle";
    }
    return 0;
}