Best counter example woul be a triangle that has one edge as the equator, and the other two runing to one of the poles (north ot south, doesn't matter).
the two angles at the equator are both 90 degrees, and the angle at the pole can be anything up to 180, so the three angles can add up to anywhere from 180 to 360.
As Skewbrow says, that's only on a curved surface, where the straight lines (like the equator) are actually curved. In a plane, it's always 180 (aka pi).