Given the vertex a (1,4) of △ ABC, if point B is on the Y axis and point C is on the line y = x, then the minimum perimeter of △ ABC is______ .

Given the vertex a (1,4) of △ ABC, if point B is on the Y axis and point C is on the line y = x, then the minimum perimeter of △ ABC is______ .

According to the graph, make the symmetry point m of a about y axis, make the symmetry point D of a about y = x, connect MD intersection line y = x and C, intersect Y axis at B, then the perimeter of △ ABC is the minimum, that is, the length of DM is the minimum perimeter of triangle