If the triangles in the figure are similar, what is the length of side b? a. 36 b. 40 c. 32.4 d. 45

If both triangles are similar, you need to find a scale factor from triangle ABC to triangle DEF. to do so, you must compare the sides you know (BC=9 and EF=90). How do you get from 9 to 90? You multiply 9 by 10. Now, since AC is similar to DF, and you know DF=360, you divide by your scale factor of 10 to get the length of AC, which is 36