Calculate circumference and area of a circle from its diameter

void setup()
{
    size(500, 500);
    int r = 300; //ค่ารัศมี
    float ac; //Area of circle
    float lc; //Area of line
    ac=PI*r*r; //สูตรหาพื้นที่
    lc=2*PI*r; //สูตรหาเส้นรอบรูป
    println("Value of ac = "+ac);
    println("Value of lc = "+lc);
    ellipse(250, 250, r, r);
    fill(0);
    textSize(11);
    text("Area = 282743.3388230814", 150, 240);
    text("Circumference of circle = 1884.9555921538758", 150, 270);
    }