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Learn how to identify and draw dilations, differentiate between enlargements and reductions, and find scale factors with examples and solutions.
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7.6 ESSENTIAL QUESTION • How do you identify and draw dilations?
A dilation is called a reduction if the image is smaller than the original figure. • A dilation is called an enlargement if the image is larger than the original figure.
a. b. SOLUTION a. The dilation is an enlargement because the image (P'Q'R') is larger than the original figure (PQR). b. The dilation is a reduction because the image (X'Y'Z' ) is smaller than the original figure (XYZ). Example 1 Identify Dilations Tell whether the dilation is a reduction or an enlargement.
a. b. SOLUTION Find the ratio of CP' to CP. CP' CP' 2 6 a. scale factor = = = CP CP 3 3 b. scale factor = = 2 Example 2 Find Scale Factors Find the scale factor of the dilation.
Checkpoint 1. 3. 2. enlargement; 2 ANSWER 1 reduction; ANSWER 3 3 reduction; ANSWER 7 Identify Dilations and Find Scale Factors Tell whether the dilation is a reduction or an enlargement. Then find the scale factor of the dilation.
SOLUTION Q'R' = Write a proportion. QR 6 Substitute 8 for CP', 14 for CP, 6 for Q'R', and x for QR. = CP' x CP 8·x= 14 · 6 Cross product property 8 8x = 84 Multiply. 14 x=10.5 Divide each side by 8. Example 3 Dilations and Similar Figures P'Q'R' is the image of PQR after a reduction. Find the value of x.
Checkpoint 4. 5 ANSWER 5. 2 ANSWER Dilations and Similar Figures The red figure is the image of the blue figure after a dilation. Find the value of the variable.
Solve the proportion. 1. 4 = 9 2. 49 = n y = 11 n = 84 x = 32 x = 20 ANSWER ANSWER ANSWER ANSWER 7 x 12 45 Find the value of the variable. 3. 4.
Because and = = , QS || PT. ANSWER 5. Given the diagram, determine whether QSis parallel to PT. 8 8 48 56 1 1 6 7
Homework • Worksheet 7.6A