It's possible to demonstrate and prove mathematically that the angle sum of every triangle is 180 degrees. The techniques used are useful for solving all kinds of other geometry problems too.

By the numbers: Among Americans age 25 and up with a bachelor's degree or better who moved to a new county in 2023, 6.1% went to NYC, 3.5% to D.C. and 3.2% to Dallas. The Triangle's share was ...