Pink triangle and the LGBT rights movement. In Nazi concentration camps, each prisoner was required to wear a downward-pointing, equilateral triangular cloth badge on their chest, the color of which identified the reason for their imprisonment. Early on, homosexual male prisoners were variously identified with a green triangle (indicating criminals) or red triangle (political prisoners), the number "175" (referring to Paragraph 175, the section of the German penal code criminalizing homosexual activity), or the letter "A" (which stood for "Arschficker", literally "ass fucker"). Later, the use of a pink triangle was established for prisoners identified as homosexual men, which also included bisexual
Reuleaux triangle three-cornered shape of the Reuleaux triangle may be seen both as a symbol of the Trinity, and as "an act of opposition to the form of the circle". The Reuleaux triangle has also been used in other styles of architecture. For instance, Leonardo da Vinci sketched this shape as the plan for a fortification. A modern high-rise building, the Kölntriangle in Cologne, Germany, was built with a Reuleaux triangle cross-section. Together with the circular shape of its core, this gives varied depths to the rooms of the building. Another early application of the Reuleaux triangle, by Leonardo da Vinci circa