 Adapted from Walch Education Investigating Scale Factors.

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Adapted from Walch Education Investigating Scale Factors

Key Concepts 1.1.2: Investigating Scale Factors 2 The notation is as follows: D k (x, y) = (kx, ky). Multiply each coordinate of the figure by the scale factor when the center is at (0, 0).

Concepts, continued… 1.1.2: Investigating Scale Factors 3 The lengths of each side in a figure also are multiplied by the scale factor. If you know the lengths of the preimage figure and the scale factor, you can calculate the lengths of the image by multiplying the preimage lengths by the scale factor. The dilation is an enlargement if k > 1, a reduction if 0 < k < 1, and a congruency transformation if k = 1.

Let’s Practice 1.1.2: Investigating Scale Factors 4 A triangle has vertices G (2, –3), H (–6, 2), and J (0, 4). If the triangle is dilated by a scale factor of 0.5 through center C (0, 0), what are the image vertices? Draw the preimage and image on the coordinate plane.

Step 1 1.1.2: Investigating Scale Factors 5 Start with one vertex and multiply each coordinate by the scale factor, k. D k = (kx, ky)

Step 2 1.1.2: Investigating Scale Factors 6 Repeat the process with another vertex. Multiply each coordinate of the vertex by the scale factor.

Step 3 1.1.2: Investigating Scale Factors 7 Repeat the process for the last vertex. Multiply each coordinate of the vertex by the scale factor.

Step 4 1.1.2: Investigating Scale Factors 8 List the image vertices.

Step 5 1.1.2: Investigating Scale Factors 9 Draw the preimage and image on the coordinate plane.

Your turn. 1.1.2: Investigating Scale Factors 10 What are the side lengths of with a scale factor of 2.5 given the preimage and image to the right and the information that DE = 1, EF = 9.2, and FD = 8.6?

Thanks for watching! Ms. Dambreville