I started the ruler and compass series a while ago and am just now getting back to it. Here is my construction of a perpendicular bisector of a given line segment.
First, I drew a line segment:
Using my compass (which quickly gave out on me), I made two big fat arcs. They have the same radius – this is important.
Where those two cross, I drew a line. That line is the perpendicular (at 90 degree angle to) bisector (splits in in two equal pieces) of the original segment:
Why does it work?
Well, that’s a great question. I’m sure there’s some proof of why this actually results in splitting the original line segment in half with a perpendicular line. I’ll have to think on it more.
But intuitively it totally feels right.
Now that’s a bad way to proceed with math, but it’s a great first start!
How about you?
Do you like to play with ruler and compass constructions? Do you know why this works?
Oh – and if you don’t have one, buy a compass here (that’s the one I just bought to replace my junky one).
And I also ordered this cool book about Compass Drawings – I’m so excited!
You might also like:
- What is a Ruler and Compass Construction?
- GeoGebra – Overcoming the Fear
- Geometry with Cheese
- Math Picture Book: Sir Cumference and the Great Knight of Angleland
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