Respuesta :

They are similar!

21 ÷ 15 = 1.4

5 x 1.4 = 7
8 x 1.4 = 11.2

Since the scale factor for the enlargement of all of the sides is the same, the triangles are mathematically similar!
4. The triangles are similar because the corresponding sides are in the same proportion.

21/15 = 7/5 = 11.2/8