## Detailed description of the polygon tool

The TactiForma set contains tools to create regular polygon shapes with five, six, seven, eight or nine corners referred to as pentagon, hexagon, heptagon, octagon and nonagon respectively.

The radius of the polygons range from three to eight centimetres.

The magnetic foot is an essential part of the regular polygon tool, to hold the tool in place.

**Foreword**

The regular polygon shape and the regular polygon tool itself need some more explanation than other TactiForma tools for a good understanding. Especially the regular polygon section in the design story of the TactiForma provides more background about the design requirements.

In order to use the regular polygon tool, using pushpins is recommended.

**The regular polygon shape based on triangles**

A regular polygon is a shape where the individual sides are all of the same length.

It can also be described as a circle filled up with isosceles triangles. The sides of two adjacent triangles co-inside. The sides of the triangles are not present in the drawing. Only the base sides are visible as the sides of the polygon shape.

For later on: Each triangle of the regular polygon is called a segment.

**Global description of the tool**

To understand the setup of the tool, imagine a line drawing of an isosceles triangle pointing upwards. The base side is horizontal. The top corner is above the middle of the base side. The angles for the respective top corners of the pentagon, hexagon, heptagon, octagon and nonagon are 72, 60, 51, 45, and 40 degrees.

The top of the triangle is going to be the centre of the polygon. The tool is rotating around this centre point while shifting from one segment on to the next.

The two sides of the triangle are in fact the rulers to measure and set the radius of the polygon.

**Body of the tool**

Keep the triangle from above in mind. The equal sides of the triangle are rulers, the legs of the tool. An important detail; the right ruler goes along the outside of the triangle, the left ruler along the inner side of the triangle. In effect the rulers are placed asymmetric. This comes in handy when drawing. See drawing instructions.

Both rulers would meet in the top corner, but a top section of the triangle is cut off and replaced with a ring, so the rulers are only partly present.

The hole in the ring leaves space to find the centre position of the polygon and is also the fit for the magnetic foot to hold the tool in place during the rotation of the tool.

**Tactile properties**

The legs have a centimetre indication at the top surface and along the side indents at every half centimetre. At the outer side of the right leg, medium sized indents are provided to indicate the type of polygon. E.g. six indents means the hexagon polygon tool.

Seen from the centre point, the ruler goes from three to eight centimetres.

Each ruler has a pushpin marker near to the ring and at the end.

The ring has an inner radius of nearly two centimetres and an outer radius of nearly three centimetres. Three small indents are at the outside of the ring.

One of them is placed on the line formed by the bisector. Two others on an orthogonal line that crosses the centre position.

The round foot has two magnets fully encapsulated in rubber, to hold the body of the tool in place. It is lacking a section so the fingertip can slide in. This open area is called finger entrance. It enables exploring the drawing near the polygons centre area.

The vertical groove in the middle of the finger entrance indicates the precise centre position of the polygon. The groove can partly surround a pushpin.

For more information, have a look at the Polygon Tool Manual page.