function setup() {

  createCanvas(600, 600);

  x1 = random(width);

  x2 = random(width);

  y1 = random(height);

  y2 = random(height);

}

​

function draw() {

  background(220);

  ellipse(x1,y1,10);

  ellipse(x2, y2, 10);

  line(x1, y1, mouseX, mouseY);

  line(x2,y2,mouseX,mouseY);

  let v3 = createVector(mouseX-x1, mouseY-y1);

  let v4 = createVector(mouseX-x2, mouseY-y2);

  let dotp = v3.dot(v4);

  let dist1 = v3.mag();

  let dist2 = v4.mag();

  let angle = acos(dotp/(dist1*dist2));

  let textangle = round(degrees(angle),2)

  textSize(20);

  text(textangle + " degrees", width/2, height/2);

}

​

function mousePressed() {

  x1 = random(5, width-5);

  x2 = random(5, width-5);

  y1 = random(5, width-5);

  y2 = random(5, width-5);

}