ctx.beginPath();
ctx.moveTo(, );
ctx.arcTo(, , , , );
;
The arc is drawn by connecting the last point in the subpath at (000, 000) to the first point in the arc at (000, 000) with a straight line.
Then the first point in the arc is connected to the second point at (000, 000) with another straight line, forming a corner.
A circle with radius 000 is wedged into the corner so that it touches both lines. This circle forms the arc that rounds out the corner.