Android : Draw rectangles on line of circle on a canvas in android

I'm drawing a circle and I want on the circle line rectangles that are rotated in the right degree. Like on this image:

With the help off someone on SO I've found a way to do that (almost).

I've got this:

Like you see there are 2 things missing:

1) they are not on the circle line 2) They are not rotated

I know how to rotate on a canvas in android but then they are all mixed up.

This is my code:

    int r = 200;

    canvas.save();
    mPaint.setStyle(Paint.Style.STROKE);

    canvas.translate(rect.width() / 2, rect.height() / 2);
    canvas.drawCircle(0, 0, r, mPaint);
    mPaint.setStyle(Paint.Style.FILL);

    for (int alpha = 0; alpha <= 360; alpha += 20) {

        double x = r/3 * Math.cos(Math.toRadians(alpha));
        double y = r/3 * Math.sin(Math.toRadians(alpha));
        canvas.translate((float)x, (float)y);
        canvas.drawRect(0, 0, 70, 20, mPaint);

    }
    canvas.restore();

Can someone point me out on what I'm doing wrong, why they aren't showing on the line of the circle? And second how to rotate, because when I do canvas.rotate(alpha) they aren't in a circle anymore.