Finding the Center of a Circle
I found some woodworking videos on how to find the center of a circle. I found a flaw in one of the methods; that's what this pair of applets is about. For reference, the videos are
Davids Diy Reviews
Tomahawk DIY
The first applet resembles the second method from the Davids Diy Reviews video. If you are eyeballing the placement of the two corners--even if you've made sure they cross the circle at the same distances from their vertices--you might not get a perfect square. It looked to me like the example in the video suffered from this effect a little.
I suspect that the above method was a modification of something like the first method shown in the Tomahawk DIY video. That method really does work, but wastes some effort. An inscribed right angle is subtended by a semicircle, so the latter method produces two short chords and a diameter with each placement of the corner.
It is not necessary to align these diameters so that the two corner placements create a square. The next applet shows what happens if you just draw two inscribed right angles and the chords where they cross the circle (these chords being diameters).
Well, now YouTube thinks I want more videos about finding the center of a circle. I thought this one by Heartwood Art was quick and clever.