Useful algebra funtions

triutil.pde

int getTriangleArea(Triangle t){
     int v1 = distance(t.p1.x, t.p1.y, t.p2.x, t.p2.y);
     int v2 = distance(t.p2.x, t.p2.y, t.p3.x, t.p3.y);
     int v3 = distance(t.p3.x, t.p3.y, t.p1.x, t.p1.y);
     int s = (v1 + v2 + v3) / 2;
     return (int) sqrt(s * (s - v1) * (s - v2) * (s - v3));
}

int distance(float x1, float y1, float x2, float y2){
     return (int) Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}

//http://en.wikipedia.org/wiki/Solution_of_triangles#Three_sides_given_.28SSS.29
boolean isAcute(Triangle t){
     int v1 = distance(t.p1.x, t.p1.y, t.p2.x, t.p2.y);
     int v2 = distance(t.p2.x, t.p2.y, t.p3.x, t.p3.y);
     int v3 = distance(t.p3.x, t.p3.y, t.p1.x, t.p1.y);
     double aA = acos((v2*v2 + v3*v3 - v1*v1) / (2.0*v2*v3)) * (180.0 / PI); 
     double aB = acos((v1*v1 + v3*v3 - v2*v2) / (2.0*v1*v3)) * (180.0 / PI); 
     double aC = (180.0 - aA - aB); 
     if(aA < 90 && aB < 90 && aC < 90){
          return true;
     }else{
          return false; 
     }
}