We can see that through angles A and C that this triangle is an isosceles triangle. Knowing that, we can set up the equation 3x=4x-2. We can simplify by adding 2 two both sides. We get the equation 3x+2=4x. Then we subtract 3x from both sides. So therefore, 2=x. Length AB is 3x so we would do 2*3, which is equal to 6. So your answer would be B. 6.
