Final answer:
In similar figures, corresponding sides match up. In this case, the person's shadow in the smaller triangle corresponds to the shadow of the flag pole in the larger triangle, and the longest side of the large triangle corresponds to the longest side of the small triangle.
Step-by-step explanation:
In similar figures, corresponding sides are the sides that match up between the two figures. In the given diagram of two similar triangles, the person's shadow in the smaller triangle corresponds to the shadow of the flag pole in the larger triangle. The longest side of the large triangle corresponds to the longest side of the small triangle.