9 1 Perimeter and Circumference Warm Up Problem
9 -1 Perimeter and Circumference Warm Up Problem of the Day Lesson Presentation Lesson Quizzes
9 -1 Perimeter and Circumference Math Journal (5 Min) • Venn Diagram - Each student will be given the title/title’s of the lesson that will be taught that day. They must then, at the beginning of class, construct a Venn Diagram by drawing 2 overlapping circles and fill out information in each circle on the topic’s (will be 2 topics) about what they know about the topic’s before they have been taught the lesson, and at the end of class, look over and refine their pervious Venn Diagram with information that they now know about the topic after they have been taught the lesson. Then, each student will discuss his/her answers within their group. Finally, to leave class, each student will have to give/write 1 common and different characteristic that they now know that pertained to the lesson. (Remember in a Venn Diagram: Unique characteristics of the two topics being compared are recorded in the outer of the two overlapping circles. Common characteristics are recorded where the circles overlap).
9 -1 Perimeter and Circumference Homework Review (5 Min)
9 -1 Perimeter and Circumference Warm Up Add or multiply. 1. 8. 2 + 5. 6 + 8. 2 + 5. 6 27. 6 2. 12. 4 + 15. 8 + 9. 3 37. 5 3. 22 · 3. 14 69. 08
9 -1 Perimeter and Circumference Problem of the Day A rectangular piece of sheet metal measures 5 in. by 6 in. A rectangular 7 notch 1 in. deep and in. wide is cut 64 out of the middle of each side. What is the perimeter of the piece after the cuts have been made? (Hint: You don’t have to use fractions. ) 30 in. (22 in. plus 8 in. for the eight 1 in. cuts)
9 -1 Perimeter and Circumference Textbook Examples (I Do) (5 Min)
9 -1 Perimeter and Circumference Learn to find the perimeter of a polygon and the circumference of a circle.
9 -1 Perimeter and Circumference Vocabulary perimeter circumference pi
9 -1 Perimeter and Circumference Perimeter is the distance around a geometric figure. To find the perimeter P of a polygon, you can add the lengths of its sides.
9 -1 Perimeter and Circumference Additional Example 1: Finding the Perimeter of a Polygon Find the perimeter. 25 cm 15 cm P = 25 + 15 Use the side lengths. P = 65 Add. The perimeter of the triangle is 65 cm.
9 -1 Perimeter and Circumference Check It Out: Example 1 Find the perimeter of the polygon. 25 cm 20 cm 30 cm P = 25 + 20 + 30 Use the side lengths. P = 75 Add. The perimeter of the triangle is 75 cm.
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference Additional Example 2: Using Properties of a Rectangle to Find Perimeter Find the perimeter of a rectangle. 14 ft 18 ft P P = = 2 l + 2 w Use the formula. (2 · 18) + (2 · 14) Substitute for l and w. Multiply. 36 + 28 Add. 64 The perimeter of the rectangle is 64 ft.
9 -1 Perimeter and Circumference Check It Out: Example 2 Find the perimeter of a rectangle. 16 ft 8 ft P P = = 2 l + 2 w (2 · 16) + (2 · 8) 32 + 16 48 Use the formula. Substitute for l and w. Multiply. Add. The perimeter of the rectangle is 48 ft.
9 -1 Perimeter and Circumference The distance around a circle is called circumference. For every circle, the ratio of circumference C to diameter d is the same. This ratio, C , is d represented by the Greek letter , called pi. Pi is approximately equal to 3. 14 or 22. By solving the 7 C equation = for C, you get the formula for d circumference.
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference Additional Example 3 A: Finding the Circumference of a Circle Find the circumference of the circle to the nearest tenth. Use 3. 14 for . 12 in. C = d You know the diameter. C 3. 14 · 12 Substitute for and d. C 37. 68 Multiply. The circumference of the circle is about 37. 7 in.
9 -1 Perimeter and Circumference Additional Example 3 B: Finding the Circumference of a Circle Find the circumference of the circle to the nearest tenth. Use 3. 14 for . 18 cm C = 2 r You know the radius. C 2 · 3. 14 · 18 Substitute for and r. C 113. 04 Multiply. The circumference of the circle is about 113. 0 cm.
9 -1 Perimeter and Circumference Check It Out: Example 3 A Find the circumference of the circle to the nearest tenth. Use 3. 14 for . 7 in. C = d C 3. 14 · 7 You know the diameter. C 21. 98 Multiply. Substitute for and d. The circumference of the circle is about 22. 0 in.
9 -1 Perimeter and Circumference Check It Out: Example 3 B Find the circumference of the circle to the nearest tenth. Use 3. 14 for . 11 cm C = 2 r You know the radius. C 2 · 3. 14 · 11 Substitute for and r. C 69. 08 Multiply. The circumference of the circle is about 69. 1 cm.
9 -1 Perimeter and Circumference Helpful Hint If the diameter or radius of a circle is a 22 multiple of 7, use for . 7
9 -1 Perimeter and Circumference Additional Example 4: Application The diameter of a circular pond is 42 m. What is its circumference? Use 22 for . 7 C = d You know the diameter. C 22 · 42 7 1 22 · 42 6 C 7 1 1 C 132 Substitute 22 for and 42 for d. 7 Write 42 as a fraction. Simplify. Multiply. The circumference of the pond is about 132 m.
9 -1 Perimeter and Circumference Check It Out: Example 4 The diameter of a circular spa is 14 m. What is its circumference? Use 22 for . 7 C = d You know the diameter. C 22 · 14 7 1 22 · 14 2 C 7 1 1 C 44 Substitute 22 for and 14 for d. 7 Write 14 as a fraction. Simplify. Multiply. The circumference of the spa is about 44 m.
9 -1 Perimeter and Circumference Class work Problems (We Do) (10 Min) • Pg. 362 -363 (1 -10)
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference Small Group CW(Yall Do) (10 Min) • Pg. 362 -363 (12 -30 EOE)
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference
9 -1 Perimeter and Circumference Homework (You Do) (10 Min) • Pg. 362 -363 (11, 15, 17, 21, 25 odd)
9 -1 Perimeter and Circumference Math Journal (5 Min) • Venn Diagram - Each student will be given the title/title’s of the lesson that will be taught that day. They must then, at the beginning of class, construct a Venn Diagram by drawing 2 overlapping circles and fill out information in each circle on the topic’s (will be 2 topics) about what they know about the topic’s before they have been taught the lesson, and at the end of class, look over and refine their pervious Venn Diagram with information that they now know about the topic after they have been taught the lesson. Then, each student will discuss his/her answers within their group. Finally, to leave class, each student will have to give/write 1 common and different characteristic that they now know that pertained to the lesson. (Remember in a Venn Diagram: Unique characteristics of the two topics being compared are recorded in the outer of the two overlapping circles. Common characteristics are recorded where the circles overlap).
9 -1 Perimeter and Circumference Lesson Quizzes Standard Lesson Quiz for Student Response Systems
9 -1 Perimeter and Circumference Lesson Quiz Find the perimeter. 1. 8 m 12 m 10 m 6 m 9 m 2. 8 in. 45 m 36 in. 10 in. 3. What is the circumference of a circle with a a radius of 8 inches? Use 3. 14 for . 50. 24 in. 4. If a guardrail is to be placed around the edge of a circular swimming pool with a diameter of 21 ft, how many feet of railing will be needed? Use 22 for . 66 ft 7
9 -1 Perimeter and Circumference Lesson Quiz for Student Response Systems 1. Identify the perimeter. A. 10 in. B. 15 in. C. 24 in. D. 48 in. 6 in.
9 -1 Perimeter and Circumference Lesson Quiz for Student Response Systems 2. Identify the perimeter. A. 52 m B. 82. 5 m C. 165 m D. 330 m 18 m 8 m
9 -1 Perimeter and Circumference Lesson Quiz for Student Response Systems 3. What is the circumference of a circle with a radius of 13 in. ? Use 3. 14 for . A. 40. 82 in. B. 81. 64 in. C. 265. 33 in. D. 530. 66 in.
9 -1 Perimeter and Circumference Lesson Quiz for Student Response Systems 4. Jill plans to build a fence around her circular garden. About how many feet of fencing would be required if the garden has a diameter of 28 ft? A. 88 ft B. 66 ft C. 44 ft D. 22 ft
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