Geometry Honors TNReady Flashcard 4

Front

What is a transformation in geometry?

Back

A transformation is an operation that moves or changes a shape in some way to produce a new shape, called the image.

Front

Define rotation in geometry.

Back

Rotation is a transformation that turns a figure around a fixed point, called the center of rotation, by a specified angle.

Front

What is the effect of a 90-degree clockwise rotation on a point (x, y)?

Back

The new coordinates after a 90-degree clockwise rotation are (y, -x).

Front

What is the effect of a reflection across the y-axis on a point (x, y)?

Back

The new coordinates after reflection across the y-axis are (-x, y).

Front

What is a dilation in geometry?

Back

Dilation is a transformation that changes the size of a figure but not its shape, using a scale factor.

Front

How do you determine the scale factor in a dilation?

Back

The scale factor is determined by the ratio of the lengths of corresponding sides of the original figure and the image.

Front

What is the rule for translating a point (x, y) by (a, b)?

Back

The rule for translation is (x, y) → (x + a, y + b).

Front

What is the image of point G after a 135° clockwise rotation about point O in a regular octagon?

Back

The image of point G after a 135° clockwise rotation about point O is point B.

Front

What does congruence mean in geometry?

Back

Congruence means that two figures have the same shape and size, and can be made to coincide by a series of transformations.

Front

What is the significance of the origin in transformations?

Back

The origin (0, 0) is often used as a reference point for rotations and dilations in the coordinate plane.