Geometry > The Involute of a square and other shapes

Learning outcome:

I can trace and name the locus of a string end as it unwinds from a plane geometric figure i.e. involute.

By the end of the lesson I will be able to:

Draw one revolution of an involute

Draw a part revolution of an involute (or a combination of)

Design my own shapes using the involutes

Before studying this lesson I need to make sure that I know how to:

Draw a radial lines

Draw a neat freehand curve

The Involute of a square

An Involute is the locus of a point of a string as it unwinds from a square. This involute is drawn using compasses To see an example of this you can visit:

Note that the line forming the involute is the green one as it is the one that lies on the end of the string.