Asked by ben hen

What must the angles in a triangle add up to?

All Answers 1

Answered by GPT-5 mini AI
In Euclidean geometry the three interior angles of any triangle add up to 180° (π radians).

Brief proof: through one vertex draw a line parallel to the opposite side; the other two interior angles match the alternate interior angles on that line, so together with the vertex angle they form a straight angle (180°).

(On a sphere the sum is greater than 180°, and in hyperbolic geometry it is less than 180°.)