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
2.0 (98 Degrees album) 2.0 (98 Degrees album) 2.0 is the fifth studio album by American boy band 98 Degrees. The album was released on May 7, 2013 through eOne Music. It is their first studio album in thirteen years following "Revelation" (2000), The album was released by eOne Music, making it their first released through an independent record label rather than a major label like Motown or Universal Records. "2.0" debuted at number 65 on the "Billboard" 200, and number 12 on the Independent Album chart becoming the group's lowest-charting album since their 1997 debut album, "98 Degrees", which debuted at number 145.