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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              <canvas id="what-is-a-circumcenter" resize="true"></canvas>
            
          
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              html,
body {
	padding: 0;
	margin: 0;
	width: 100%;
	height: 100%;
	overflow: hidden;
}
            
          
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              paper.install(window);
var SQRT_3 = Math.pow(3, 0.5);
var red = '#F79C82';
var lightRed = '#FDE6E0';
var grey = '#8A90A4';
var blue = '#89C2EF';
var green = '#95D9AD';
var lightGrey = '#969CAE';
var triangle;

var randomNumber = function(minimum, maximum) {
  return Math.random() * (maximum - minimum) + minimum;
};

window.onload = function() {
  paper.setup('what-is-a-circumcenter');
  triangle = new Triangle(calcA());
  paper.view.draw();

  paper.view.onFrame = function (event) {
    project.clear();
    triangle.update();
  };
};

window.onresize = function() {
  project.clear();
  console.log(calcA());
  triangle.resize(calcA());
};

var calcA = function() {
  return Math.max(250, Math.min(paper.view.size.width, paper.view.size.height) - 400);
};



// ---------------------------------------------------
//  Triangle
// ---------------------------------------------------
var Triangle = function(a) {
  var center = new Path.Circle(new Point(paper.view.center), 0.5);
      center.strokeColor = red;
  var centerLabel = new PointText(paper.view.center.x, paper.view.center.y + 15);
      centerLabel.content = '(0,0)';
      centerLabel.fillColor = grey;
      centerLabel.justification = 'center';
  this.resize(a);
  this.a = a;
  this.counter = 0;
};

Triangle.prototype.resize = function(a) {
  // Offset
  var x_off = paper.view.center.x;
  var y_off = paper.view.center.y;
  this.circumcenter = new Point(x_off, y_off);
  // The points of the triangle
  this.pts = [new paper.Point(0 + x_off, -a / SQRT_3 + y_off),
              new paper.Point(-a/2 + x_off, a * 0.5 / SQRT_3 + y_off),
              new paper.Point(a/2 + x_off, a * 0.5 / SQRT_3 + y_off)];
  // Labels
  this.labels = ['(0, -a/√3)',
                 '(-a/2, /2√3)',
                 '(a/2, a/2√3)'];
  this.AnimatedCircle = new AnimatedCircle(new Point(x_off, y_off),
                                                     a / SQRT_3);
  this.reset(a);
};

Triangle.prototype.reset = function(a) {
  // To track state of lines to animate them
  this.s_now = [this.pts[0], this.pts[2], this.pts[1]];
  this.b_now = [this.pts[0], this.pts[2], this.pts[1]];
  this.counter = 0;
  this.AnimatedCircle.reset();
  // Bisecting arcs and lines
  this.bisectors = [];
  this.buildBisectors(a);
};

Triangle.prototype.buildBisectors = function(a) {
  for (var i = 0; i < 2; i++) {
    this.bisectors.push(new Bisector(i===2 ? true : false));
  };
  var a1 = a * randomNumber(0.51, 0.55);
  var a2 = a * randomNumber(0.51, 0.55);
  var a3 = a * randomNumber(0.51, 0.55);
  this.bisectors[0].addArc(this.pts[0], this.pts[2].subtract(this.pts[0]).angle, -27, 27, a1);
  this.bisectors[0].addArc(this.pts[2], this.pts[0].subtract(this.pts[2]).angle, -27, 27, a1);
  this.bisectors[1].addArc(this.pts[1], this.pts[0].subtract(this.pts[1]).angle, -27, 27, a3);
  this.bisectors[1].addArc(this.pts[0], this.pts[1].subtract(this.pts[0]).angle, -27, 27, a3);
};

Triangle.prototype.update = function(time) {
  // Draw Sides
  this.sideVector(this.pts[0], this.pts[2], this.labels[0], [0, -20], 0);
  this.sideVector(this.pts[2], this.pts[1], this.labels[1], [0, 25], 1);
  this.sideVector(this.pts[1], this.pts[0], this.labels[2], [0, 25], 2);
  // Animation Timeline
  if (this.counter >= 180)
    this.bisectors[0].draw();
  if (this.counter >= 220)
    this.bisectors[1].draw();
  if (this.counter >= 255)
    this.drawCircumcenter();
  if (this.counter >= 280)
    this.AnimatedCircle.draw();
  if (this.counter >= 500)
    this.reset(this.a);
  this.counter++;
};

Triangle.prototype.sideVector = function(vectorStart, e, coord_label, coord_offset, i) {
  var vector = e.subtract(vectorStart);
  var end = vectorStart.add(vector);
  // Draw Side
  var path = this.animateSide(vectorStart, end, this.s_now, i);
      path.strokeWidth = 1;
      path.selected = true;
      path.selectedColor = blue;
  // Draw Labels
  var text = new PointText(vectorStart.x + coord_offset[0], vectorStart.y + coord_offset[1]);
      text.content = coord_label;
      text.fillColor = grey;
      text.justification = 'center';
};

Triangle.prototype.animateSide = function(u, v, now, i) {
  var delta = v.subtract(now[i]);
  now[i] = now[i].add(delta.divide(20));
  return new Path([u, now[i]]);
};

Triangle.prototype.drawCircumcenter = function() {
  var rectangle = new Path.Rectangle(this.circumcenter, 5);
      rectangle.strokeColor = red;
      rectangle.fillColor = '#fff';
      rectangle.position = this.circumcenter;
  // Label BG
  var rectangle = new Path.Rectangle(this.circumcenter, [150, 40]);
      rectangle.fillColor = '#fff';
      rectangle.position = new Point(this.circumcenter.x, this.circumcenter.y + 30);
  // Draw Label
  var text = new PointText(new Point(this.circumcenter.x, this.circumcenter.y + 25));
      text.content = 'The Circumcenter \n (0,0)';
      text.fillColor = grey;
      text.justification = 'center';
};



// ---------------------------------------------------
//  Bisector
// ---------------------------------------------------
var Bisector = function(track) {
  this.arcs = [];
  this.intersections = [];
  this.uniqueId = Math.round(Math.random()*10000);
  this.track = track;
};

Bisector.prototype.addArc = function(center, delta, start, end, r) {
  this.arcs.push(new Arc(center, delta, start, end, r));
};

Bisector.prototype.reset = function() {
  for (var i = this.arcs.length - 1; i >= 0; i--) {
    this.arcs[i].reset();
  };
  this.animatedLine && this.animatedLine.reset();
};

Bisector.prototype.draw = function() {
  this.arcs[0].draw();
  if (this.arcs[0].drawComplete) {
    this.arcs[1].draw();
    // Get the intersection points of the two curves
    this.intersections = this.getIntersections();
    // If there are 2 intersections, draw a line between them
    if (this.intersections.length == 2 && !this.animatedLine) {
      this.offsetIntersections();
    }
    // The animated line is defined, draw it
    if (this.animatedLine) {
      var path = this.animatedLine.draw();
      path.strokeWidth = 1;
      path.strokeColor = red;
    }
    // Draw the intersection points
    this.drawIntersections();
    if (this.track)
      console.log(this.intersections.length)
  }
};

Bisector.prototype.offsetIntersections = function() {
  var alpha = Math.PI * this.intersections[1].point.subtract(this.intersections[0].point).angle / 180;
  var beta = Math.PI * this.intersections[0].point.subtract(this.intersections[1].point).angle / 180;
  var a = this.intersections[1].point.add(new Point(100 * Math.cos(alpha),
                                                    100 * Math.sin(alpha)));
  var b = this.intersections[0].point.add(new Point(100 * Math.cos(beta),
                                                    100 * Math.sin(beta)));
  this.animatedLine = new AnimatedLine(b, a, 10);
};

Bisector.prototype.getIntersections = function() {
  return this.arcs[0].path.getIntersections(this.arcs[1].path);
};

Bisector.prototype.drawIntersections = function() {
  for (var i = 0; i < this.intersections.length; i++) {
    new Path.Circle({
      center: this.intersections[i].point,
      radius: 2,
      strokeColor: lightGrey,
      fillColor: '#fff'
    });
  }
};



// ---------------------------------------------------
//  Arc
// ---------------------------------------------------
var Arc = function(center, delta, start, end, r) {
  this.center = center;
  this.delta = delta;
  this.start = start;
  this.end = end;
  this.arcSpan = this.start;
  this.r = r;
  this.drawComplete = false;
};

Arc.prototype.reset = function() {
  this.arcSpan = this.start;
  this.drawComplete = false;
};

Arc.prototype.draw = function() {
  var angle = this.delta + this.arcSpan;
  var start = this.delta + this.start;
  var end = this.delta + this.end;

  var s = Math.PI * start / 180;
  var now = Math.PI * angle / 180;
  var now_half = s + (now - s)/2;

  var from = this.center.add(new Point(this.r * Math.cos(s),
                                       this.r * Math.sin(s)));
  var through = this.center.add(new Point(this.r * Math.cos(now_half),
                                          this.r * Math.sin(now_half)));
  var to = this.center.add(new Point(this.r * Math.cos(now),
                                     this.r * Math.sin(now)));
  this.path = new Path.Arc({
    from: from,
    through: through,
    to: to,
    strokeWidth: 1,
    strokeColor: lightRed
  });
  if (angle < end)
    this.arcSpan += Math.abs(this.end - this.start)/10;
  if(Math.abs(angle - end) < 1)
    this.drawComplete = true;
};



// ---------------------------------------------------
//  Animated Line
// ---------------------------------------------------
var AnimatedLine = function(u, v, decc) {
  this.u = u;
  this.v = v;
  this.now = u;
  this.decc = decc;
};

AnimatedLine.prototype.reset = function() {
  this.now = this.u;
};

AnimatedLine.prototype.draw = function() {
  var delta = this.v.subtract(this.now);
  this.now = this.now.add(delta.divide(this.decc));
  return new Path([this.u, this.now]);
};



// ---------------------------------------------------
//  Animated Circle
// ---------------------------------------------------
var AnimatedCircle = function(center, r) {
  this.center = center;
  this.r = r;
  this.angle = 0;
};

AnimatedCircle.prototype.reset = function() {
  this.angle = 0;
};

AnimatedCircle.prototype.draw = function() {
  var from = this.center.add(new Point(this.r * Math.cos(0),
                                       this.r * Math.sin(0)));
  var now = Math.PI * this.angle / 180;
  var now_half = Math.PI * (this.angle - Math.abs(this.angle / 2)) / 180;
  now_half = now_half <= 0 ? 0 : now_half;
  var through = this.center.add(new Point(this.r * Math.cos(now_half),
                                          this.r * Math.sin(now_half)));
  var to = this.center.add(new Point(this.r * Math.cos(now),
                                     this.r * Math.sin(now)));
  if (this.angle >= 360) {
    var path = new Path.Circle(center, this.r);
        path.strokeColor = green;
  } else {
    var path = new Path.Arc(from, through, to);
        path.strokeColor = green;
  }
  this.angle += (360 - this.angle) / 10;
};
            
          
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