Since Angle A B C and B C A are congruent. It means that they are equal. An isosceles triangle is a triangle that has two equal sides and two equal base angles. Since Angle A B C and B C A are equal, it means that the triangle is an isosceles triangle. It also means that sides AC and AB are equal. The expression becomes
3x - 7 = 2x
3x - 2x = 7
x =7
To determine the length of line segment AC. We will substitute x = 7 into 3x - 7. It becomes