Triangle Theorems Every Student Should Know in 2026
The complete list of triangle theorems for geometry: angle sum, exterior angle, triangle inequality, congruence (SSS SAS ASA AAS HL), similarity, and special tr
How to Find Missing Angles of Triangles
To find a missing interior angle of a triangle, add the two known angles and subtract their sum from 180°. For example, if two angles are 45° and 56°, the third is 180° − 101° = 79°. All three interior angles must add to 180°.
