createCanvas(600, 600);

  noLoop();

}

​

function draw() {

  background(220);

  beginShape()

    var a1 = random(150,450);

    var a2 = random(150,450);

    vertex(a1, a2);

    fill(color("red"));

    ellipse(a1, a2, 5);

    fill(color("white"));

    var b1 = random(150,450);

    var b2 = random(150,450);

    vertex(b1, b2);

    fill(color("blue"));

    ellipse(b1, b2, 5);

    fill(color("white"))

    var c1 = random(150,450);

    var c2 =random(150,450);

    vertex(c1, c2);

    fill(color("green"));

    ellipse(c1, c2, 5);

    fill(color("white"))

    vertex(a1, a2);

  endShape()

  let x = ((a1*a1 + a2*a2 - b1*b1 - b2*b2)*(a2-c2) -(a1*a1 + a2*a2 - c1*c1 - c2*c2)*(a2 - b2))/(2*(a1 - b1)*(a2-c2) - 2*(a1-c1)*(a2-b2));

    let y = ((a1*a1 + a2*a2 - c1*c1 - c2*c2)*(a1-b1) -(a1*a1 + a2*a2 - b1*b1 - b2*b2)*(a1 - c1))/(2*(a1 - b1)*(a2-c2) - 2*(a1-c1)*(a2-b2));

  fill(color("blue"));

  ellipse(x, y, 10);

  noFill();

  ellipse(x, y, 2*dist(x,y,a1,a2));

}

​