# Getting x and y coordinates along a curve

Aim: to get (x,y) coordinates for circles along an arc.

Hi,

I have been trying to plot circles along an arc and get their locations. I wonder if there is some theta stuff that I need to look into…

this is the design that I want to achieve, along with an array that stores their coordinates.

this is the result of the following code:

``````let r;
let theta;

function setup() {
createCanvas(710, 400);
// Initialize all values
r = height * 0.45;
theta = 0;
}

function draw() {
background(255);

// Translate the origin point to the center of the screen
translate(width / 2, height / 2);

// Convert polar to cartesian
for(var theta = 0; theta<180; theta+=20){
let x = r * cos(theta);
let y = r * sin(theta);
ellipseMode(CENTER);
noStroke();
fill(255,0,0);
ellipse(x, y, 32, 32);
}
``````

Many thanks.

Angles need to be expressed as radians not degrees

``````    let x = r * cos(radians(theta));
let y = r * sin(radians(theta));

``````
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