Acute and obtuse triangles "x", then If two obtuse triangles have sides ("a, b, c") and ("p, q, r") with "c" and "r" being the respective longest sides, then The Calabi triangle, which is the only non-equilateral triangle for which the largest square that fits in the interior can be positioned in any of three different ways, is obtuse and isosceles with base angles 39.1320261...° and third angle 101.7359477...°. The equilateral triangle, with three 60° angles, is acute. The Morley triangle, formed from any triangle by the intersections of its adjacent angle trisectors, is equilateral and hence acute. The golden triangle is the isosceles
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