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.

The Pollux-Mars and Castor-Mars sides of the Triangle measure about 7 degrees in length ... formed by Mars and Castor and the right angle at Pollux. Thereafter, the appearance of a triangle ...

A triangle pointing right which indicates this ... The Range Rover Sport PHEV climbed 999 steps at a 45 degrees angle. It was part of the Dragon Challenge at Heaven’s Gate, on Tainmen Mountain ...