CAD drawing, how to draw the following picture as required, how to calculate Boolean operation, I don't understand, who can trust me, thank you.

A figure, two concentric circles, a big circle and a small circle; The great circle intersects with six equal and evenly distributed circles; The great circle also intersects with six equal and evenly distributed round-headed rectangles; The red circle is the center of a rounded rectangle, not the geometric shape of the figure.

The graph of Figure B is obtained by Boolean operation from the graph of Figure A, and the method is as follows:

This area will be transformed by the graph of Boolean operation, which is closed, that is, the ends of line segments are connected and there is no opening. Region, input; Select all circles except the red circle, and then press Enter to complete the range conversion.

Subtract, input; Select the Great Circle and press Enter; Select six circles, six round rectangles and small circles, and then press enter. This program is called difference set, that is, a big circle subtracts six circles, subtracts six round-headed rectangles, and subtracts a small circle to equal a figure B. This is the geometric figure subtraction operation. The operation of geometric figures is often called Boolean operation in CAD, the addition operation of geometric figures is called union, and the common part of geometric figures is called intersection. As can be seen from the above example, intersecting geometry can be operated by Boolean operation.

Boolean operation is used for two-dimensional graphics. First, the two-dimensional graph is converted into a region, otherwise the Boolean operation cannot be performed.