Given:
The coordinates of point A are (7,4).
It is dilated from the origin by a scale factor r = 3.
To find:
The coordinates of A'.
Solution:
If a figure is dilated from the origin by a scale factor k, then
Here, the figure is dilated from the origin by a scale factor 3, so the rule of dilation is given by:
Using this rule, we get
Therefore, the coordinates of point A' are (21,12).