Detailed explanation of C language programming problem: can any three sides form a triangle, output the area of the triangle and judge its type

problem ： Judge whether the triangle can be formed according to the three sides of the input triangle , If you can , Then output its area and judge the type of the triangle .

Ideas ：

1、 Judge whether three sides can form a triangle ： The sum of any two sides is greater than the third 、 The difference between any two sides is less than the third side .（ Here is an example of the former ）

2、 The triangle area formula （ Helen's formula is used here ）： Half circumference    

Triangle area

3、 The type of triangle ： Equilateral triangle 、 an isosceles triangle 、 right triangle 、 General triangle

Code ：

#include  <stdio.h>
#include  <math.h>
int main()
{
	float  a, b, c;// Define the three sides of a triangle as a、b、c
	float  p, S;// Define the half circumference of a triangle p、 area S
	scanf("%f,%f,%f",&a, &b, &c);// Enter any three sides 
	if ((a+b>c) && (a+c>b) &&(b+c>a))// The sum of any two sides of a triangle is greater than the third 
	{
		p = (a + b + c) / 2;// Half circumference 
		S = sqrt(p * (p - a) * (p - b) * (p - c));
		printf(" The area of the triangle is ： % f\n", S);
		if ((a==b) && (b==c))// Three sides equal 
			printf(" Equilateral triangle \n");
		else  if ((a==b)||(b==c)||(a==c))// Any two sides are equal 
			printf(" an isosceles triangle \n");
		else  if ((a * a + b * b == c * c) || (a * a + c * c == b * b) || (c * c + b * b == a * a))// Pythagorean theorem 
			printf(" right triangle \n");
		else  printf(" General triangle \n");
	}
	else  printf(" Cannot form a triangle \n");
	return 0;
}

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