In ΔABC, mÐA = 40, mÐB = 70, and AC = 5 centimeters. Find the length of AB in centimeters.
Since , it follows that since the sum of the measures of the angles of a triangle is 180 degrees.
If two angles of a triangle are congruent, then the triangle is isosceles.
If the triangle is isosceles then the sides opposite the congruent angles are congruent.