If two angles of one triangle are congruent to two angles of another triangle, then the third angles are also congruent.

Given

Triangles ABC, EFG


Prove


Proof
1:
- Given

2: - From 1

3:
- In a triangle, the sum of the measures of the interior angles is 180°

4: - From 3

5: - substitute 2 in 4

6: - From 5

Isosceles Triangle

Isosceles Triangle

Isosceles Triangle hasTwo equal sides.
By the isosceles triangle theorem, the two angles opposite the equal sides are themselves equal

Equilateral Triangle

Equilateral Triangle

Equilateral Triangle has Three equal sides, and Three equal angles, always 60°.