1. Holt CA Course 1 10-1 Perimeter Warm Up Warm Up Lesson Presentation Lesson Presentation California Standards California StandardsPreview

2. Holt CA Course 1 10-1 Perimeter Warm Up 1. What figure has four equal sides and four right angles? 2. What figure has eight sides? 3. What figure has five sides? square octagon pentagon

3. Holt CA Course 1 10-1 Perimeter AF3.1 Use variables in expressions describing geometric quantities (e.g., P = 2w + 2l, A = bh, C =  d–the formulas for the perimeter of a rectangle, the area of a triangle, and the circumference of a circle, respectively). Also covered: AF1.1, AF1.2, AF3.2 California Standards 1212

4. Holt CA Course 1 10-1 Perimeter Vocabulary perimeter

5. Holt CA Course 1 10-1 Perimeter The perimeter of a polygon is the sum of the lengths of its sides.

6. Holt CA Course 1 10-1 Perimeter

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

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

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

10. Holt CA Course 1 10-1 Perimeter Additional Example 3: Finding Unknown Side Lengths and the Perimeter of a Polygon Find each unknown measure. B. What is the perimeter of the polygon? Step 1: Find b. Find the sum of the lengths opposite side b. b = 50 + 22 b = 72 P = 72 + 55 + 50 + 33 + 22 + 22 P = 254 Step 2: Find the perimeter. The perimeter of the polygon is 254 cm.

11. Holt CA Course 1 10-1 Perimeter l = 4w Find the length. l = (4 19) l = 76 Substitute 19 for w. Multiply. Additional Example 3: 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? 4w4w 19 cm

12. Holt CA Course 1 10-1 Perimeter Additional Example 3C Continued P = 2 l + 2 w Substitute 76 and 19. P = 2(76) + 2(19) P = 152 + 38 P = 190 Multiply. Add. Use the formula for the perimeter of a rectangle. The perimeter of the rectangle is 190 cm. 4w4w 19 cm

13. Holt CA Course 1 10-1 Perimeter Check It Out! Example 1 Find the perimeter of the figure. 3.3 + 3.3 + 4.2 + 4.2 + 3 Add all the side lengths. 3.3 in. 4.2 in. 3 in. The perimeter is 18 in.

14. Holt CA Course 1 10-1 Perimeter Check It Out! Example 2 Find the perimeter P of the parallelogram. P = 2l + 2w Substitute 15 for l and 2 for w. P = (2 15) + (2 2) P = 30 + 4 P = 34 Multiply. Add. The perimeter is 34 cm. 15 cm 2 cm

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

16. Holt CA Course 1 10-1 Perimeter Lesson Quiz: Part I 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? 9 cm 4 ft 112 cm 5 6 __

17. Holt CA Course 1 10-1 Perimeter Lesson Quiz: Part II 4. What is the perimeter of a rectangle with length 22 cm and width 8 cm? 5. The width of a rectangle is 12 in. What is the perimeter of the rectangle if the length is 7 in. longer than the width? 60 cm 62 in.