Triangle ABC is an issoceles triangle with a base of AB .

Answer:
a = 3
Step-by-step explanation:
given that triangle ABC is isosceles , then the legs are congruent (equal), so
AC = BC ( substitute values )
6a - 8 = 4a - 2 ( subtract 4a from both sides )
2a - 8 = - 2 ( add 8 to both sides )
2a = 6 ( divide both sides by 2 )
a = 3