Question

Triangle ABC is similar to triangle DEF.

What is the scale factor of triangle DEF to triangle ABC?
Triangle A B C and triangle D E F are drawn. Side A B is labeled 9. Side A C is labeled 12. Side D E is labeled 3. Side D F is labeled x.

3

1/3

4

1/4
Triangle ABC is similar to triangle DEF.
What is the scale factor of triangle DEF to triangle ABC?
Triangle A B C and triangle D E F are drawn. Side A B is labeled 9. Side A C is labeled 12. Side D E is labeled 3. Side D F is labeled x.

3

1/3

4

1/4

Answer 1

If we were to solve for the missing side :
9 = 12
3 x
(12) (3) = (9) x
36 = 9 x
9 9
4 = x
Missing side DF = 4

The ratio of the side of the triangles are 9:3 and 12:4
Side length 9 is * 3 of corresponding side length 3
Side length 12 is * 3 of corresponding side length 4.

The scale factor of these to triangles is 3 because triangle ABC is 3 times bigger than triangle DEF.

:)