This is a device to trisect angle (BAC). A and D are fixed points and E moves on their line. (ADFB) and (DFEC) are rhombi. Lines (AD) and (AF) trisect the angle (BAC). Later is modified by moving (Ctrl+2) E on line AD.
For a mechanical device (linkage) to trisect angles with this principle see YatesTrisector.html . Discussion by H. Brocard, Bulletin de la S.M.F 3(1875), p. 47-48.
![[alogo]](alogo.png){kind=small}
Laisant's trisector ![[0_0]](Laisant_Trisector_files/Laisant_Trisector_0_0_0.png)
![[0_1]](Laisant_Trisector_files/Laisant_Trisector_0_0_1.png)