What did the little acorn say when he grew up? Geometry (Gee, I’m a tree)!

Sorry for the ‘teacher’ joke.

As soon as we begin to enquire about *shapes,* we are ‘speaking’ geometry. Originally, it was the mathematics of measuring the Earth, surveying blocks of land for farming, for example. In Egypt, geometry was used to replace boundary markers between properties after the Nile flooded each year. The term geometry comes from the Greek words γη (ge-) or γαια (Gaia) meaning earth, ground or land, and μέτρον (métron) meaning measure.

Geometry can be regarded as the discipline of studying abstract shapes with their properties and relationships. It can also be thought of in very practical terms. Tradespeople use geometry every day of their lives, making sure walls or frames are square, having the correct gradients for trusses, roofs, pathways, stormwater, etc. I have workmen on my roof at the moment, replacing corrugated iron sheeting. The art of cutting the sheeting to fit involves some clever geometry!

All the different facets of geometry result from our asking curious questions. At least, *someone* asked these questions:

- how do these shapes compare? ~ Congruency and Similarity
- how can I alter (or not alter) these shapes? ~ Transformations and Symmetry
- how do shapes fit together? ~ Tessellations
- how can I calculate distances/lengths diagonally across objects? ~ Pythagoras’ Theorem
- how can I measure lengths and angles inside circles and what properties do circles have? ~ Circle Geometry
- how can different places be connected? ~ Graph Theory
- what does ‘being connected’ mean, and what fundamental properties of shapes are preserved when a shape is distorted? ~ Topology

I enjoyed your presentation and no it wasn’t too long. Each subtraction algorithm has its merit as you demostrated, but after learning the “one up and one down” method, I’m employing it because of its speed and ease of usage. Even my wife, who hates mathematics with a passion, thinks it’s too easy. I look forward to your future presentations on both multiplication and number theory. I read an introduction text book some twenty five years ago on number theory by Oystein Ore who taught at Yale for better than twenty years. So in closing, please produce these lectures and the longer the better. Thanks.

Dennis Bell (on a CCM YouTube video about How to Subtract (Large) Numbers Easily)

See all Testimonials