Battle of the Iron Triangle ending a bitter four-month struggle. Following the withdrawal from Base 82 COSVN organized a new corps headquarters in the Tay Ninh- Binh Long region and designated it the 301st Corps. This corps would soon direct the combat operations of the 7th and 9th NVA Divisions, separate regiments, and additional formations already en route from North Vietnam. Meanwhile General Thuần decided to rest the tired troops of the 5th Division and turned his attention to sending his 25th Division to clear out the PAVN bases in the Ho Bo area west of the Iron Triangle. The ARVN defenses around An Dien
Triangle their internal angles, measured here in degrees. A triangle that has two angles with the same measure also has two sides with the same length, and therefore it is an isosceles triangle. It follows that in a triangle where all angles have the same measure, all three sides have the same length, and such a triangle is therefore equilateral. Triangles are assumed to be two-dimensional plane figures, unless the context provides otherwise (see Non-planar triangles, below). In rigorous treatments, a triangle is therefore called a "2-simplex" (see also Polytope). Elementary facts about triangles were presented by Euclid in books 1–4