Chapter 10 of 10All chapters
Chapter 10 of 10
Geometry in the world
Where it actually gets used.
Everyday uses
Fitting furniture, estimating materials, planning a route, hanging shelves square. A tape measure and Pythagoras settle more arguments than any amount of eyeballing.
- The 3-4-5 triangle checks a right angle with nothing but a tape measure.
- Triangles are rigid, which is why bracing and trusses use them.
Beyond flat
On a sphere the angles of a triangle add to more than 180 degrees, which is why flight paths look curved on a flat map and why every map projection distorts something.