Question

How to understand the Triangle-sum Theorem?

Answer 1

Its Simple All the angles in a triangle adds up to 180°

Explanation:

∠A + ∠ B + ∠C = 180° NO matter what. You can also use this in inverse If you have two out of three angles then you can add the two angles you have and subtract the from 180 to get the measurement of the 3rd angle.

Hope this helps