Every few years I decide to have a go at using a CAD package for the creation of 3D diagrams…

### The world’s best map projection

As is well known, you can’t squash the surface of a sphere (or of a hemisphere) flat without either tearing…

### Let’s hear it for Logo (3)

Logo is of course known for its turtle graphics, and such is the appeal that there are now turtle graphics…

### The derivative of sin(x)

We know that we can use the limit definition     to compute the derivative of “from first principles”. And…

### Curious results of an incorrect “theorem”

I hope all readers of this blog (all three of you – you know who you are!) have heard of,…

### The size of the Solar System (and more)

I’ve been looking up at the sky at night recently, and thinking about the sizes of things.  Now it’s all…

### Neusis constructions (4): the Delian problem

The Delian problem is that of constructing ; since the polynomial equation is irreducible over the equation can’t be solved…

### Neusis constructions (3): the regular heptagon

The regular heptagon (seven sided polygon) is the smallest polygon which can't be constructed used Euclidean compass and straight-edge.  However,…

### “Neusis” constructions (2): trisections

Here we show how the use of neusis can be used to trisect arbitrary angles. In fact, we shall give…

### “Neusis” constructions (1)

As you know, the geometry of the ancient Greeks, as exemplified by Euclid, restricted constructions to the use of unmarked…