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© Copyright 2000, Jim Loy
It interactively demonstrates the actual trisection of an angle, apparently invented by C. A. Laisant in 1875. Move the bright red dot in order to change the angle. That dot is a hinge, as are the other red dots that far from the vertex. The two red dots farthest from the vertex are hinges for the short bars, but slide along the angle trisectors. The whole device is just a couple of parallelograms and a couple diagonals.
We cannot use a pair of compasses and a straightedge to trisect a general angle. That has been proven. But we can make other tools (such as the device simulated here) to trisect such an angle. In fact, we can use a pair of compasses and a straightedge to make this device. All that this device does is triple the smallest angle.
The above Java interactive demonstration was created with Cinderella (a geometry program).
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