Question

编程题：编写程序输入三角形的3条边长，计算并输出三角形的面积。

Answer 1

一、程序分析

三角形面积海伦公式：√[ p ( p - a ) ( p - b ) ( p - c ) ] 。其中 p = (a + b + c) / 2 。a、b、c分别是三角形的三边长。 

二、根据三角形面积计算公式用if语句编写程序如下：

#include "stdio.h"

#include "math.h"

int main(void)

{

float a = 0, b = 0, c = 0, p = 0;

float area = 0;

printf("Please input three sides of triangle:");

scanf_s("%f %f %f", &a, &b, &c);

if((a + b) > c && (a + c) > b && (b + c) > a)

{

p = (a + b + c) / 2;

area = sqrt(p * (p - a) * (p - b) * (p - c));

}

else

printf("Triangle does not exist！\n");

printf("The area of triangle is:%f\n", area);

return 0;

扩展资料：

还可以使用switch语句计算三角形的面积，编写程序如下

#include "stdio.h"

#include "math.h"

int main(void)

{

float a = 0, b = 0, c = 0;

float p = 0;

printf("Please input three sides of triangle:");

scanf_s("%f %f %f", &a, &b, &c);

switch (a + b > c  &&  a + c > b && b + c > a)

{

case 0:printf("Triangle does not exist！\n"); break;

case 1:

p = (a + b + c)*0.5;

printf("The area of triangle is:%f\n", sqrt(p * (p - a) * (p - b) * (p - c)));

break;

}

return 0;

}

参考资料：百度百科-switch

参考资料：百度百科-结束条件语句