Math 2: CW 3.4 Dilations (with review)

Front

What is a dilation in geometry?

Back

A dilation is a transformation that alters the size of a figure but not its shape, using a scale factor.

Front

What is a scale factor in dilations?

Back

The scale factor is a number that scales, or multiplies, the dimensions of a figure during a dilation.

Front

How do you dilate a point (x, y) by a scale factor k?

Back

The new coordinates after dilation are (kx, ky).

Front

What is the effect of a scale factor greater than 1 on a figure?

Back

A scale factor greater than 1 enlarges the figure.

Front

What is the effect of a scale factor between 0 and 1 on a figure?

Back

A scale factor between 0 and 1 reduces the size of the figure.

Front

What is the rule for a 270° clockwise rotation about the origin?

Back

The rule is (x, y) → (-y, x).

Front

What is the rule for a 90° counterclockwise rotation about the origin?

Back

The rule is (x, y) → (-y, x).

Front

How do you find the scale factor when dilating from point A (x1, y1) to point A' (x2, y2)?

Back

The scale factor k is found using k = (x2/x1) = (y2/y1).

Front

What is the image of the point (a, b) after a 180° rotation about the origin?

Back

The image is (-a, -b).

Front

What is the image of the point (a, b) after a 270° counterclockwise rotation about the origin?

Back

The image is (b, -a).