Triangle Theorem Notes
Triangle Sum Theorem
The sum of the interior angles of a triangle is 180°.
Isosceles Triangle Theorem
Part 1) The base angles of an isosceles triangle are
congruent.
Part 2) If the base angles of a triangle are congruent, then
the triangle is isosceles.
Equilateral Triangle Theorem
The interior angles of an equilateral triangle are congruent.
Examples
1) Find 𝑚∠𝐴
2) Find the value of 𝑥 if 𝑚∠2 = 16𝑥 − 1.
2) Find the measure of the angle marked with “?”.