let H=600;

let t=0;

let a=250;

let b=150;

let points=[];

let l1,l2;

function setup() {

  createCanvas(800, 600);

  background(355,255,255);

}

​

function draw() {

  background(355,255,255);

  translate(W/2,H/2);

  stroke('BLACK');

for(i=0;i<points.length;i++){

    point(points[i].x,points[i].y);

  }

  strokeWeight(5);

  stroke('RED')

  point(-150,0);

  point(150,0);

  push()

    noStroke();

 text("S'",-150,0);

   text("S",150,0);

  pop();

  stroke('GREEN')

  point(a*cos(t),b*sin(t));

  push()

  noStroke();

 text("P",a*cos(t),b*sin(t));

  pop();

  stroke('BLUE');

  points.push({x:a*cos(t),y:b*sin(t)});

  l1=dist(-150, 0, a*cos(t),b*sin(t));

    l2=dist(150, 0, a*cos(t),b*sin(t));

  strokeWeight(2);

  line(-150,0,a*cos(t),b*sin(t));

    line(150,0,a*cos(t),b*sin(t));

  stroke('ORANGE');

​

  push();

  noStroke();

  fill('PURPLE');

  textSize(20);

  text("SP+S'P=2a",00,200);

  pop();

​

​

  t=t+0.005;

​

}