If the angles in a triangle don't add up to 180o then I think that means the triangle is not on a flat plane. An example would be if you took a point on the eq

If the angles in a triangle don't add up to 180o then I think that means the triangle is not on a flat plane. An example would be if you took a point on the equator of the earth, moved East or West 1/4 of the earth's circumference and took another point and then projected those two points North until they met at the pole, you would have a triangle with 3 interior right angles.