Select each of the statements that are true about dilations...

Select each of the statements that are true about dilations in a plane. In a dilation, the measures of the angles of the preimage differ from the measure of the angles in the image. In a dilation, similarity is preserved. In a dilation, congruence of corresponding sides is preserved. In a dilation, the preimage size and the image size are not the same and are therefore considered isometries. In a dilation, all corresponding sides of a preimage and image have the same proportion.

Transcript

00:05 Here we're trying to determine which statements are true about dilations of figures.

00:10 So just as a reminder what a dilation is, a dilation is a transformation that either causes a figure to get smaller or larger.

00:20 So it grows inside or it shrinks in size.

00:27 So for our purposes, what are properties of a dilation? well, everything in the figure when it's dilated, stays the same except the size, right? so a dilation is really just a change in size.

00:46 Now, let's look at the choices here.

00:56 The first one is when a figure is dilated is angles change measure.

01:00 So when we refer to a dilation, a dilation does not change angle measures because a dilation is just a change in size, not the actual shape.

01:10 So if the angles changed in size or changed in angle measures, then the shape would no longer be the same.

01:18 So not number one because when you dilate a figure, the angles don't change.

01:23 Okay.

01:24 The next one is dialysis to parallel lines to parallel lines.

01:27 Well, let's think about it.

01:28 If i have this line and it's three centimeters and i multiply it by a scale factor of two, what happens to the line? the length of the line just gets longer.

01:42 So instead of it being three centimeters, it is now going to be six centimeters.

01:49 So it didn't change the slope of the line.

01:51 It didn't change anything about the line besides its length...

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