centre of conic section

例句：

1. 1. Thecentre of the circle is the point whereall the circles intersect.
   圆的中心是所有圆相交的点。
2. 2. The centreof the cone is thepoint where all the conesintersect.
   锥体的中心是所有锥体相交的点。
3. 3. The centreof the figure is thepoint where all the lines intersect.
   图形的中心是所有线相交的点。