Special right triangle : , which follows immediately from the Pythagorean theorem. Of all right triangles, the 45°–45°–90° degree triangle has the smallest ratio of the hypotenuse to the sum of the legs, namely . Of all right triangles, the 45°–45°–90° degree triangle has the greatest ratio of the altitude from the hypotenuse to the sum of the legs, namely . Triangles with these angles are the only possible right triangles that are also isosceles triangles in Euclidean geometry. However, in spherical geometry and hyperbolic geometry, there are infinitely many different shapes of right isosceles triangles. This is a triangle whose three angles
Frank (given name) Frank (given name) Frank is a masculine given name. Ultimately from the Germanic tribal name of the Franks, in the early medieval Frankish Empire, the status of being "a Frank" became synonymous with that of a free man; hence also the English adjective "frank" (Middle English, from Old French "franc", 12th century). Use as a given name seems to arise already in the Carolingian period; the Old High German form "Francho, Franko" is on record from the 8th century. While "Frank" is a given name in its own right, in fact reflecting the Old Frankish form "*Frank", the given name