Iron Brigade and was previously called the "Black Hat" Brigade. The 3rd Brigade Combat Team, 1st Infantry Division was known as the Iron Brigade from its formation in 1917 through World War I, World War II and Vietnam, until some time in the early 2000s when, for reasons that are still unclear, the name was changed to Duke Brigade. The unit crest was an Iron Cross in a triangle, it appears that that was also changed. The 3rd Brigade of the 4th Infantry Division is also known as the Iron Brigade. Its unit crest is similar to the medals issued to veterans
Conway triangle notation Conway triangle notation In geometry, the Conway triangle notation, named after John Horton Conway, allows trigonometric functions of a triangle to be managed algebraically. Given a reference triangle whose sides are "a", "b" and "c" and whose corresponding internal angles are "A", "B", and "C" then the Conway triangle notation is simply represented as follows: where "S" = 2 × area of reference triangle and in particular Furthermore the convention uses a shorthand notation for formula_14 and formula_15 Hence: Some important identities: where "R" is the circumradius and "abc" = 2"SR" and where "r" is the incenter, formula_22 and formula_23