Answer:
BC = 18 units
Explanation:
given the base angles B and C are congruent ( same arcs ) then the triangle is isosceles with legs AB and AC congruent , that is
AB = AC ( substitute values )
8x - 4 = 5x + 11 ( subtract 5x from both sides )
3x - 4 = 11 ( add 4 to both sides )
3x = 15 ( divide both sides by 3 )
x = 5
Then
BC = 4x - 2 = 4(5) - 2 = 20 - 2 = 18 units