Saccheri–Legendre theorem Saccheri–Legendre theorem In absolute geometry, the Saccheri–Legendre theorem states that the sum of the angles in a triangle is at most 180°. Absolute geometry is the geometry obtained from assuming all the axioms that lead to Euclidean geometry with the exception of the axiom that is equivalent to the parallel postulate of Euclid. The theorem is named after Giovanni Girolamo Saccheri and Adrien-Marie Legendre. The existence of at least one triangle with angle sum of 180 degrees in absolute geometry implies Euclid's parallel postulate. Similarly, the existence of at least one triangle with angle sum of less than 180 degrees
The Three Degrees at The Royal Albert Hall" (aka "An Evening with The Three Degrees"), was recorded in October 1979 in which the trio were backed by the Royal Philharmonic Orchestra. In 1980, the compilation album "Gold" was released and became a UK Top 10 hit. Featuring one side of their hits on the Ariola label between 1978–79, and one side of live recordings from their 1979 Royal Albert Hall television special, this would be the trio's second "best of" compilation to make the UK Top 10 in less than two years, after CBS released "A Collection of their 20 Greatest Hits" in