Sentence examples for a pentagon from inspiring English sources

The phrase "a pentagon" is correct and usable in written English.
It can be used when referring to a five-sided polygon or in contexts related to the U.S. Department of Defense, which is often referred to as "the Pentagon."
Example: "The architect designed a new building in the shape of a pentagon to stand out in the city skyline."
Alternatives: "a five-sided figure" or "a five-sided polygon."