A triangle with vertices at [tex]\( A(20, -30) \)[/tex], [tex]\( B(10, -15) \)[/tex], and [tex]\( C(5, -20) \)[/tex] has been dilated with a center of dilation at the origin. The image of [tex]\( B \)[/tex], point [tex]\( B' \)[/tex], has the coordinates [tex]\( (2, -3) \)[/tex].

What is the scale factor of the dilation?

A. [tex]\(\frac{1}{10}\)[/tex]
B. [tex]\(\frac{1}{5}\)[/tex]
C. 5
D. 10



Answer :

To determine the scale factor of the dilation, we'll compare the coordinates of the original point [tex]\( B \)[/tex] with the coordinates of its image [tex]\( B' \)[/tex].

1. Original coordinates of [tex]\( B \)[/tex]:
[tex]\[ B = (10, -15) \][/tex]

2. Coordinates of the image [tex]\( B' \)[/tex]:
[tex]\[ B' = (2, -3) \][/tex]

3. The scale factor of the dilation can be found by comparing the corresponding coordinates of [tex]\( B \)[/tex] and [tex]\( B' \)[/tex].

We need to look at the ratio of the x-coordinates:
[tex]\[ \text{Scale factor (x-coordinate)} = \frac{2}{10} = 0.2 \][/tex]

Similarly, we look at the ratio of the y-coordinates:
[tex]\[ \text{Scale factor (y-coordinate)} = \frac{-3}{-15} = 0.2 \][/tex]

4. Both the x and y coordinates give us the same scale factor, which is [tex]\( 0.2 \)[/tex].

5. We can see that the scale factor matches for both coordinates, so the uniform scale factor of dilation is [tex]\( 0.2 \)[/tex].

6. Converting [tex]\( 0.2 \)[/tex] to a fraction, we get:
[tex]\[ 0.2 = \frac{1}{5} \][/tex]

Thus, the scale factor of the dilation is [tex]\( \frac{1}{5} \)[/tex].

Therefore, the correct answer is:
[tex]\[ \boxed{\frac{1}{5}} \][/tex]