How to draw a circle's polar line with a geometric artboard

the specific steps are as follows:

Step one draws circles and circles outside the point

Open the Geometry artboard, click the Circle tool on the left sidebar, draw a circle above the canvas, click the left sidebar "point tool", and draw a point outside the circle, as shown in the following figure.

To draw a point sample outside of a circle in a geometric artboard

　　Step two draw the polar line of the circle

1. Click on the left sidebar "custom Tool"--circle tool-pole line;

Select the Pole Line tool sample under the Geometry Artboard Customization Tool

2. Move the mouse to the front of the production of the above click, and then move the mouse to the outside of the production point Click to make a good polar line, as shown in the following figure.

Example of polar line drawing a circle using the Polar line tool