Question

Triangle ABC will be dilated according to the rule


`D_(F, 0.25) (x,y)`, where point F is the center of dilation.

What will be the coordinates of vertex A' of the image?


a. (-8,-4)

b. (-2,-1)

c. (0, 0)

d. (1, 0)


The answer is (1,0), but could someone explain how you get it, please?

Answer 1

D 1,0

Explanation:

credit to the one up above

Answer 2

Usually dilations have a center of dilation at the origin (0,0). When this occurs all we need to do is multiply each coordinate by the dilation scale. Unfortunately things get a little more complicated when the center of dilation is not at the origin.

In this case the center of dilation is located at F: (3,1)

The first step we must take is to find how many units point F is from vertex A.

In this case, F is 4 unit up and 8 units right of vertex A. (Reference the first image below to see how I found this)

Now we must multiply these dimensions (4 units and 8 units) by the factor of dilation (0.25)

4 * 0.25 = 1

8 * 0.25 = 2

This shows us how many dimensions away point
`A^(1)` is from point F:

1 unit vertically

2 units horizontally

Now how do we know if
`A^(1)` is above or below, left or right from point F? Easy! There has been no translations so the directions will be the same as the original:

Point F: (3, 1) ---> (3-2, 1-1) ---> (1, 0)

Reference the second image to see this

Hopefully this helps and makes sense. Let me know if you need further explanation or clarification.

~Just a girl in love with Shawn Mendes