Home > Draw > Regular Polygon: Center, Edge Midpoint

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A regular polygon around a center, sized out to the middle of a side.

Menu: Draw > Regular Polygon: Center, Edge Midpoint | In depth: Rectangles & squares

The tool asks how many sides first, then takes the center and the middle of one side. The distance between them is the apothem - the reach from the middle to a flat rather than to a point.

CAD calls this circumscribed, meaning the polygon sits outside a circle that touches its sides. The button says what you click instead: those words describe a circle you cannot see, and this one - the circumscribed case - has the smaller radius of the two, which is the opposite of how the name reads.

Use it when what matters is how wide the shape is across its flats: a nut, a tile that has to meet its neighbors edge to edge, a piece cut to a given width.

Regular Polygon: Center, Vertex takes the same two clicks and reads the second one as a corner. A corner is further out than a side's middle, so the same two points give a larger polygon here than they do there.

The center and the point you clicked stay yours. Every corner is derived from them - none of them is the point you clicked, since that one sits on a side rather than at a corner - so dragging either driver keeps the shape regular.

Compass and straightedge can divide a circle into n equal parts only for certain n: 3, 4, 5, 6, 8, 10, 12, 15, 16, 17, 20, 24 and so on. Seven, nine, eleven, thirteen, fourteen and eighteen are not among them. This tool places corners by angle, so it will draw any count from 3 up.

< Previous: Regular Polygon: Center, Vertex | Next: Dimension: Linear >

• Regular Polygon: Center, Vertex - the same two clicks, read as a corner.
• Regular Polygon: Edge - build from the first side instead.