Tamiko is planning a stone wall shaped like a triangle, with vertices (-1, -2), (2, 2), and (-2, 2) on a coordinate grid. She plans to add a second wall, in the same shape, enclosing the first wall, with the origin as the center of dilation. The vertices of the second wall are (-3, -6), (6, 6), and (-6, 6). a. What scale factor did Tamiko use for the second wall? b. Are the two walls similar? Explain