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Do Now 1/11/12 Take out your HW from last night. Text p. 166, #1-19 all, 23 &24 Text p. 166, #1-19 all, 23 &24 Copy HW in your planner. Text p. 170, #1-11.

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Presentation on theme: "Do Now 1/11/12 Take out your HW from last night. Text p. 166, #1-19 all, 23 &24 Text p. 166, #1-19 all, 23 &24 Copy HW in your planner. Text p. 170, #1-11."— Presentation transcript:

1 Do Now 1/11/12 Take out your HW from last night. Text p. 166, #1-19 all, 23 &24 Text p. 166, #1-19 all, 23 &24 Copy HW in your planner. Text p. 170, #1-11 all, all Text p. 170, #1-11 all, all In your journal, tell whether the figures are similar. 59° 35° 86° 119° 55° 107° 79° 107° 80° 135° 38°

2 Try it out Tell whether the figures are similar. 59° 35° 86° 119° 55° 107° 79° 107° 80° 135° 38° NP QS = ? NO QR = ? PO RS = ? = ? = ? = ? Similar Not similar; corresponding angles do not have equal measures

3 Homework Text p. 166, #1-19 all, 23 &24 1) similar 2) not similar 3) similar 4) not similar 5) not similar 6) similar 7) similar 8) not similar 9) No, corresponding angles are not equal 10) 4 in. X 6 in., 16 in. X 24 in. 11) similar 12) not similar 13) yes 14) no 15) yes 16) yes 17) no 18) no 19) no 23) C 24) No

4 Objective SWBAT use similar figures to find unknown measures

5 Section 4.4 “Similar Figures” Similar Figures Two figures are SIMILAR FIGURES if they have the same shape but not necessarily the same size. The symbol ~ indicates two figures are similar. Two figures are similar if: 1). The measures of their corresponding angles are equal 2). The ratios of the lengths of their corresponding sides are proportional (equal ratios)

6 Crossmultiply Section 4.5 “Using Similar Figures” Given ABC ~ JKL, find x and y. Angle B corresponds to Angle K y = 103°

7 Given ABCD ~ GHIJ, find HJ. G H IJ AB CD x 16 Cross multiply

8 C A B b a F D E Given ABC ~ DEF, find a. Given ABC ~ DEF, find b.

9 C A B Y Z X g f Given ABC ~ XYZ, find g and f.

10 Indirect Measurement the method of using proportions to find an unknown length or distance in similar figures

11 Indirect Measurements You measure the shadow of a telephone pole to be 24 ft. The shadow of a 5ft-tree is 4 ft. How tall is the telephone pole? S H s h

12 Indirect Measurements To estimate the height of the Transco Tower in Houston, TX, you measure its shadow to be about 55m. The shadow of a 50m flagpole is about 10m. Estimate the height of the Transco Tower. S H s h

13 City officials want to know the height of a traffic light. Estimate the height of the traffic light = h Write a proportion h = The traffic light is about 27 feet tall ft ft h ft Cross multiply. h ≈ 27 ftDivide each side by to isolate the variable. Indirect Measurements

14 Homework NJASK7 Prep Text p. 170, #1-11 all, all Text p. 170, #1-11 all, all


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