Example 44: Area of a Triangle

/* Calculate area of triangle */
#include <stdio.h>
#include <math.h>

int  isTriangleValid ( float s1, float s2, float s3 ){
	//determine if the given sides form a valid triangle
}

float areaOfTriangle (float s1, float s2, float s3) {
	//calculate the area of a triangle
}

float distance (int x1, int y1, int x2, int y2) {
	//calculate the length of the sides
}

int main() {
	int x1, y1, x2, y2, x3, y3;
	float s1, s2, s3, area;
	int isValid = 0;	

	printf ("Enter the coordinates of 3 vertices of the triangle: \n" ) ;
	printf ("First Vertex (x, y): \n" );
	scanf ("%d %d", &x1, &y1);
	printf ("Second Vertex (x, y): \n");
	scanf ("%d %d", &x2, &y2);
	printf ("Third Vertex (x, y): \n");
	scanf ("%d %d", &x3, &y3);

	s1 = distance (x1, y1, x2, y2);
	s2 = distance (x2, y2, x3, y3);
	s3 = distance (x1, y1, x3, y3);

	printf ("Length of first side = %f\n", s1);
	printf ("Length of second side = %f\n", s2);
	printf ("Length of third side = %f\n", s3);
	
	isValid = isTriangleValid (s1, s2, s3);
	if (isValid) {
		area = areaOfTriangle (s1, s2, s3);
		printf ("Area: %f\n", area);
	}
	else
		printf ("Not a triangle. \n");
	return 0;
}