Weber problem that, at the optimum, the angles between the AD, BD, and CD straight lines must be equal to 360° / 3 = 120°. Torricelli deduced from that conclusion that: 1– if any triangle ABD, whose ∠ADB angle is equal to 120°, generates an ABDE convex quadrilateral inscribed in a circle, the ∠ABE angle of the ABE triangle must be equal to (180° − 120°)= 60°; 2– one way to determine the set of locations of D for which the ∠ADB angle is equal to 120° is to draw an equilateral ABE triangle (because each angle of an equilateral triangle is
Venus Equilateral by a low-power source. Powered by batteries, the driver tube enables the multi-G constant-boost spaceships seen throughout the series. At the series opening both Mars and Venus have been colonized. Both are described as having shirt-sleeve environments in at least some regions. Eleven of the thirteen Venus Equilateral stories were published in "Astounding Science Fiction" between 1942 and 1945. They were: Smith wrote a 12th story, "Mad Holiday", for the first book collection "Venus Equilateral" (1947) (which omitted "Lost Art" and "Identity"), and a 13th story, "The External Triangle", for Harry Harrison's 1973 anthology "Astounding". All 13 stories were included