Topic 7: Dilations and Similarity

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 and a center of dilation.

Front

What does it mean for two triangles to be similar?

Back

Two triangles are similar if their corresponding angles are equal and their corresponding sides are in proportion.

Front

What is a scale factor?

Back

A scale factor is a number that scales, or multiplies, some quantity. In dilations, it determines how much larger or smaller a figure becomes.

Front

If the scale factor is greater than 1, what happens to the figure?

Back

The figure enlarges.

Front

If the scale factor is less than 1, what happens to the figure?

Back

The figure shrinks.

Front

What is the center of dilation?

Back

The center of dilation is the fixed point in the plane about which all points are expanded or contracted.

Front

How do you determine if two triangles are similar using side lengths?

Back

If the ratios of the lengths of corresponding sides are equal, the triangles are similar.

Front

What is the similarity statement for two similar triangles?

Back

The similarity statement indicates which triangles are similar, using the notation ΔABC~ΔDEF.

Front

What is the relationship between the angles of similar triangles?

Back

The corresponding angles of similar triangles are equal.

Front

How can you find the missing side length in similar triangles?

Back

Use the proportion of the corresponding sides to set up an equation and solve for the missing length.