Dilation is when you make a figure bigger or smaller like as so above.
The two figures are similar if the second can be obtained from the first by a sequence of transformations and dilation.
Transformations =dilation ,rotation,reflection,translation(dilation- is when you make the figure smaller . Rotation -is when you turn the figure.Translation- is when you just simply slide the figure.Reflection- is when you make the figure look alike a mirror image.)
First : write ratios comparing the lengths of the sides. ex. RT/R'T' = 4/9 *COUNT THE BOXES IN BETWEEN RT IN THE SMALL FIGURE AND COUNT BETWEEN RT IN THE BIG FIGURE AND MAKE IT A RATIO. Second:simply the ratio of each points you did (RT/R'T'=4/9 , ST/S'T'=5/13) AND SEE IF ITS EQUAL