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Finding Perimeter. 10-1. Course 1. Warm Up. Problem of the Day. Lesson Presentation. Finding Perimeter. 10-1. Course 1. Learn to find the perimeter and missing side lengths of a polygon. Finding Perimeter. 10-1. Course 1. Insert Lesson Title Here. Vocabulary. perimeter.

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  1. Finding Perimeter 10-1 Course 1 Warm Up Problem of the Day Lesson Presentation

  2. Finding Perimeter 10-1 Course 1 Learn to find the perimeter and missing side lengths of a polygon.

  3. Finding Perimeter 10-1 Course 1 Insert Lesson Title Here Vocabulary perimeter

  4. Finding Perimeter 10-1 Course 1 The perimeter of a figure is the distance around it. To find the perimeter you can add the lengths of the sides.

  5. Finding Perimeter 10-1 Course 1 Additional Example 1: Finding the Perimeter of a Polygon Find the perimeter of the figure. Add all the side lengths. 2.8 + 3.6 + 3.5 + 3 + 4.3 The perimeter is 17.2 in.

  6. Finding Perimeter 10-1 Course 1 Try This: Example 1 Find the perimeter of the figure. 3.3 in. 3.3 in. Add all the side lengths. 3.3 + 3.3 + 4.2 + 4.2 + 3 The perimeter is 18 in. 4.2 in. 4.2 in. 3 in.

  7. Finding Perimeter 10-1 Course 1

  8. Finding Perimeter 10-1 Course 1 Additional Example 2: Using a Formula to Find Perimeter Find the perimeter P of the rectangle. 12 cm 3 cm P = 2l+ 2w Substitute 12 for l and 3 for w. P = (2 • 12) + (2 • 3) P = 24 + 6 Multiply. P = 30 Add. The perimeter is 30 cm.

  9. Finding Perimeter 10-1 Course 1 Try This: Example 2 Find the perimeter P of the rectangle. 15 cm 2 cm P = 2l + 2w Substitute 15 for l and 2 for w. P = (2 •15) + (2 •2) P = 30 + 4 Multiply. P = 34 Add. The perimeter is 34 cm.

  10. Finding Perimeter 10-1 Course 1 Additional Example 3A: Finding Unknown Side Lengths and the Perimeter of a Polygon Find each unknown measure. A. What is the length of side a if the perimeter equals 1,471 mm? P = sum of side lengths 1,471 = 416 + 272 + 201 + 289 + a Use the values you know. Add the known lengths. 1,471 = 1,178 + a 1,471 – 1,178 = 1,178 + a – 1,178 Subtract 1,178 from both sides. 293 = a Side a is 293 mm long.

  11. Finding Perimeter 10-1 Course 1 Additional Example 3B: Finding Unknown Side Lengths and the Perimeter of a Polygon Find each unknown measure. B. What is the perimeter of the polygon? First find the unknown side length. 72 cm Find the sides opposite side b. The length of side b = 50 + 22. Side b is 72 cm long. P = 72 + 55 + 50 + 33 + 22 + 22 Find the perimeter. P = 254 The perimeter of the polygon is 254 cm.

  12. Finding Perimeter 10-1 Course 1 Additional Example 3C: Finding Unknown Side Lengths and the Perimeter of a Polygon C. The width of a rectangle is 19 cm. What is the perimeter of the rectangle if the length is 4 times the width? 4w 19 cm Find the length. l= 4w l = (4 •19) Substitute 19 for w. Multiply. l = 76

  13. Finding Perimeter 10-1 Course 1 Additional Example 3C Continued 4w 19 cm Use the formula for the perimeter of a rectangle. P = 2l + 2w Substitute 76and 19. P = 2(76) + 2 (19) P = 152 + 38 Multiply. P = 190 Add. The perimeter of the rectangle is 190 cm.

  14. Finding Perimeter 10-1 Course 1 Try This: Example 3A Find each unknown measure. A. What is the length of side a if the perimeter equals 1,302 mm? 212 mm 280 mm 250 mm a P = sum of side lengths 240 mm 1,302 = 212 + 280 + 250 + 240 + a Use the values you know. Add the known lengths. 1,302 = 982 + a 1,302 – 982 = 982 + a – 982 Subtract 982 from both sides. 320 = a Side a is 320 mm long.

  15. Finding Perimeter 10-1 Course 1 Try This: Example 3B Find each unknown measure. B. What is the perimeter of the polygon? 12 m 8 m First find the unknown side length. 14 m 4 m Find the sides opposite side b. 6 m The length of side b = 12 + 4. 16 m b m Side b is 16 m long. P = 14 + 12 + 8 + 4 + 6 + 16 Find the perimeter. P = 60 The perimeter of the polygon is 60 m.

  16. Finding Perimeter 10-1 Course 1 Try This: Example 3C C. The width of a rectangle is 13 cm. What is the perimeter of the rectangle if the length is 5 times the width? 5w 13 cm Find the length. l = 5w l = (5 •13) Substitute 13 for w. Multiply. l = 65

  17. Finding Perimeter 10-1 Course 1 Try This: Example 3C Continued 65 cm 13 cm Use the formula for the perimeter of a rectangle. P = 2l + 2w Substitute 65and 13. P = 2(65) + 2 (13) P = 130 + 26 Multiply. P = 156 Add. The perimeter of the rectangle is 156 cm.

  18. Finding Perimeter 10-1 5 __ 6 Course 1 Insert Lesson Title Here Lesson Quiz Find each perimeter. 1.2. 3. What is the perimeter of a polygon with side lengths of 15 cm, 18 cm, 21 cm, 32 cm, and 26 cm? 4. What is the perimeter of a rectangle with length 22 cm and width 8 cm? 9 cm 4 ft 112 cm 60 cm

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