Question

If the triangles in the figure are similar, what is the length of side b? A. 36 B. 40 C. 32.4 D. 45

Answer 1

Since ABC and DEF are similar then we can write:.

CB/FE = CA/FD
9/90 = b/360
b/360 = 1/10
b = 360/10
b = 36

Answer 2

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