Q&A for How to Construct Regular Polygons Using a Circle

With a normal protractor, all you can do is measure extremely carefully.

Yes.

Use Method 1 above, except that the central angles used would not be 30°, they would be 360° divided by 11, or 32¾°.

Since none of the polygons you refer to are regular polygons, they cannot be constructed using this method.

Construct a regular nonagon using the circle method: Draw a circle, and with a protractor place nine central angles of 40° each around the center (9 x 40° = 360°). Draw nine radii separating the central angles. Mark the points where the radii intersect the circumference. Draw straight lines between adjacent points on the circumference, and you've drawn a regular nonagon.

Divide 360 degrees by 7 to get an angle of 51.428571 (recurring), and choose one point on the circle. Measure the same angle successively around the circle until you reach the starting point. You should be able to link the points together.

If you're asking about irregular polygons, the answer is no. The circle method works only for regular polygons.

You would need a protractor, and you would have to locate or be given the center of the semicircle. Draw a diameter from one end of the semicircle to the other. Then mark off seven 25.7° angles around the center on one side of the diameter. Use those angles to draw six radii, which will divide the semicircle into seven equal parts.