Knowing two points of a rectangle, how can I figure out the other two?

Question

Hey there guys, I\'m learning processing.js, and I\'ve come across a mathematical problem, which I can\'t seem to solve with my limited geometry and trigonometry knowledge o

Answer 1

/* rcx = center x rectangle, rcy = center y rectangle, rw = width rectangle, rh = height rectangle, rr = rotation in radian from the rectangle (around it's center point) */

function toRectObjectFromCenter(rcx, rcy, rw, rh, rr){
    var a = {
        x: rcx+(Math.sin((rr-degToRad(90))+Math.asin(rh/(Math.sqrt(rh*rh+rw*rw)))) * (Math.sqrt(rh*rh+rw*rw)/2)), 
        y: rcy-(Math.cos((rr-degToRad(90))+Math.asin(rh/(Math.sqrt(rh*rh+rw*rw)))) * (Math.sqrt(rh*rh+rw*rw)/2))
    };
    var b = {
        x: a.x+Math.cos(rr)*rw,
        y: a.y+Math.sin(rr)*rw
    };
    var c = {
        x: b.x+Math.cos(degToRad(radToDeg(rr)+90))*rh,
        y: b.y+Math.sin(degToRad(radToDeg(rr)+90))*rh
    };
    var d = {
        x: a.x+Math.cos(degToRad(radToDeg(rr)+90))*rh,
        y: a.y+Math.sin(degToRad(radToDeg(rr)+90))*rh
    };
    return {a:a,b:b,c:c,d:d};
}