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59°. 119°. 107°. 59°. 55°. 79°. 35°. 86°. 135°. 107°. 86°. 35°. 38°. 80°. Do Now 1/11/12. Take out your HW from last night. Text p. 166, #1-19 all, 23 &24 Copy HW in your planner. Text p. 170, #1-11 all, 14-16 all In your journal, tell whether the figures are similar. 59°.
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59° 119° 107° 59° 55° 79° 35° 86° 135° 107° 86° 35° 38° 80° Do Now 1/11/12 • Take out your HW from last night. • Text p. 166, #1-19 all, 23 &24 • Copy HW in your planner. • Text p. 170, #1-11 all, 14-16 all • In your journal, tell whether the figures are similar.
59° 119° 107° 59° 55° 79° 35° 86° 135° 107° ? ? 86° 35° = = 38° ? ? 80° = = ? ? = = Try it out Tell whether the figures are similar. NP QS NO QR PO RS Not similar; corresponding angles do not have equal measures Similar 7 14 6 12 4 8 1 2 1 2 1 2
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 HomeworkText p. 166, #1-19 all, 23 &24
Objective • SWBAT use similar figures to find unknown measures
Section 4.4 “Similar Figures” 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)
Section 4.5 “Using Similar Figures” Given ABC ~ JKL, find x and y. Angle B corresponds to Angle K y = 103° Cross multiply
Given ABCD ~ GHIJ, find HJ. 30 H G x I J Cross multiply 12 A B 16 C D
Given ABC ~ DEF, find a. Given ABC ~ DEF, find b. D A 40 20 32 F E b 35 B C a
Given ABC ~ XYZ, find g and f. Z f X A 24 40 Y 25 20 B C g
Indirect Measurement the method of using proportions to find an unknown length or distance in similar figures
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? H h S s
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. H h S s
Indirect Measurements City officials want to know the height of a traffic light. Estimate the height of the traffic light. 48.75 h 27.25 15 = Write a proportion. h ft 27.25h = 731.25 Cross multiply. 27.25 ft 48.75 ft h ≈ 27 ft Divide each side by 27.25 to isolate the variable. The traffic light is about 27 feet tall.
Homework NJASK7 Prep • Text p. 170, #1-11 all, 14-16 all