Rectas y centros y incentros en el triangulo

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void incentro(float x1, float y1, float x2, float y2, float x3, float y3, float& x, float& y) {
  float d = 2.0*((y2-y1)*(x3-x1) - (x2-x1)*(y3-y1));
  x = ((y3-y1)*(x2*x2-x1*x1+y2*y2-y1*y1) + (y1-y2)*(x3*x3-x1*x1+y3*y3-y1*y1))/d;
  y = ((x1-x3)*(x2*x2-x1*x1+y2*y2-y1*y1) + (x2-x1)*(x3*x3-x1*x1+y3*y3-y1*y1))/d;
}