Right angle of what a right angle is, namely two straight lines intersecting to form two equal and adjacent angles. The straight lines which form right angles are called perpendicular. Euclid uses right angles in definitions 11 and 12 to define acute angles (those smaller than a right angle) and obtuse angles (those greater than a right angle). Two angles are called complementary if their sum is a right angle. Book 1 Postulate 4 states that all right angles are equal, which allows Euclid to use a right angle as a unit to measure other angles with. Euclid's commentator Proclus gave a
The Three Degrees following year they released a new single "Holding Back". In January 2011, Freddie Pool replaced Cynthia Garrison, who was suffering from Piriformis syndrome, as the Degrees had touring commitments to fulfill. In 2016 The Three degrees released their first full-length studio album with member Freddie Pool entitled "Strategy: Our Tribute To Philadelphia", through Cherry Red Records. The Holiday/Scott/Garrison version of The Three Degrees was the longest running formation of the group (1989–2010). The Three Degrees The Three Degrees is an American female vocal group, which was originally formed in 1963 in Philadelphia, Pennsylvania. Although a total of 15 women have