Right triangle Right triangle A right triangle (American English) or right-angled triangle (British English) is a triangle in which one angle is a right angle (that is, a 90-degree angle). The relation between the sides and angles of a right triangle is the basis for trigonometry. The side opposite the right angle is called the "hypotenuse" (side "c" in the figure). The sides adjacent to the right angle are called "legs" (or "catheti", singular: "cathetus"). Side "a" may be identified as the side "adjacent to angle B" and "opposed to" (or "opposite") "angle A", while side "b" is the side "adjacent to
Pythagoras Peak theorem concerning a right-angled triangle is well known. Pythagoras Peak Pythagoras Peak is the highest peak, 1,275 m, in the central Tula Mountains, standing along the north side of Beaver Glacier, 8 nautical miles (15 km) southeast of Mount Storer. The peak has a prominent notch, the eastern aspect being a right-angled triangle with a perpendicular northern face. It was photographed from Mount Riiser-Larsen in February 1958 by ANARE (Australian National Antarctic Research Expeditions) led by Phillip Law, but was first visited and surveyed in December 1958 by G.A. Knuckey, ANARE surveyor. It was named by the Antarctic Names Committee