Commas before conjunctions (e.g., and, or, but). When a word like and, or, and but (called conjunctions) joins two standalone sentences, you should put a comma before it. (The real name for a standalone sentence within a longer sentence is independent clause .).Words like and, or, and but are known as conjunctions.earch. When a word like and, or, and but (called conjunctions) joins two standalone sentences, you should put a comma before it. (The real name for a standalone sentence within a longer sentence is independent clause .).
1. a polygon having five angles and five sides. 2. the Pentagon, a. a building in Arlington, Va., built in the form of a pentagon and containing most of the offices of the U.S. Department of Defense. b. the U.S. Department of Defense; the U.S. military establishment. [1560â70; < Late Latin pentagÅnum < Greek pentÃ¡gÅnon, n. use of neuter of pentÃ¡gÅnos five-angled.
A pentagon has 5 sides, and can be made from three triangles, so you know what ... ... its interior angles add up to 3 Ã 180Â° = 540Â°. And if it is a regular pentagon (all angles the same), then each angle is 540Â° / 5 = 108Â°. (Exercise: make sure each triangle here adds up to 180Â°, and check that the pentagon's interior angles add up to 540Â°) The Interior Angles of a Pentagon add up to 540Â°.