Grip used compasses to draw ellipses, because he invented ellipses after making a picture. Otherwise, the circle drawn with compass should be a perfect circle. He started from the corner of the compass, because it can only be invented from the origin. Make an ellipse to use. Then an ellipse will appear in the middle. If you draw an ellipse mathematically, it is two semicircles, that is, you can draw an ellipse by drawing two circles in half.