9-1 Perimeter and Circumference Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day Lesson Quizzes Lesson Quizzes 9-1 Perimeter and Circumference Math Journal (5 Min) Venn Diagram - Each student will be given the title/titles 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 topics (will be 2 topics) about what they know about the topics 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 9-1 Perimeter and Circumference Problem of the Day A rectangular piece of sheet metal measures 5 in. by 6 in. A rectangular notch 1 in. deep and in. wide is cut 7 64 out of the middle of each side. What is the perimeter of the piece after the cuts have been made? (Hint: You dont 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 Find the perimeter. Additional Example 1: Finding the Perimeter of a Polygon 25 cm 15 cm P = Use the side lengths. P = 65 The perimeter of the triangle is 65 cm. Add. 9-1 Perimeter and Circumference Check It Out: Example 1 20 cm 25 cm 30 cm P = Use the side lengths. P = 75 The perimeter of the triangle is 75 cm. Add. Find the perimeter of the polygon. 9-1 Perimeter and Circumference 9-1 Perimeter and Circumference Find the perimeter of a rectangle. Additional Example 2: Using Properties of a Rectangle to Find Perimeter 14 ft 18 ft P = 2l + 2w P = (2 18) + (2 14) P = P = 64 The perimeter of the rectangle is 64 ft. Use the formula. Substitute for l and w. Multiply. Add. 9-1 Perimeter and Circumference Check It Out: Example 2 Find the perimeter of a rectangle. 16 ft 8 ft P = 2l + 2w P = (2 16) + (2 8) P = P = 48 The perimeter of the rectangle is 48 ft. Use the formula. Substitute for l and w. Multiply. Add. 9-1 Perimeter and Circumference CdCd The distance around a circle is called circumference. For every circle, the ratio of circumference C to diameter d is the same. This ratio,, is represented by the Greek letter , called pi. Pi is approximately equal to 3.14 or. By solving the 22 7 equation = for C, you get the formula for circumference. CdCd 9-1 Perimeter and Circumference 9-1 Perimeter and Circumference Find the circumference of the circle to the nearest tenth. Use 3.14 for . Additional Example 3A: Finding the Circumference of a Circle 12 in. C = d C 3.14 12 C You know the diameter. Substitute for and d. Multiply. The circumference of the circle is about 37.7 in. 9-1 Perimeter and Circumference Find the circumference of the circle to the nearest tenth. Use 3.14 for . Additional Example 3B: Finding the Circumference of a Circle 18 cm C = 2r C 2 3.14 18 C You know the radius. Substitute for and r. Multiply. The circumference of the circle is about cm. 9-1 Perimeter and Circumference Find the circumference of the circle to the nearest tenth. Use 3.14 for . Check It Out: Example 3A 7 in. C = d C 3.14 7 C You know the diameter. Substitute for and d. Multiply. The circumference of the circle is about 22.0 in. 9-1 Perimeter and Circumference Find the circumference of the circle to the nearest tenth. Use 3.14 for . Check It Out: Example 3B 11 cm C = 2r C 2 3.14 11 C You know the radius. Substitute for and r. Multiply. The circumference of the circle is about 69.1 cm. 9-1 Perimeter and Circumference If the diameter or radius of a circle is a multiple of 7, use for . Helpful Hint 22 7 9-1 Perimeter and Circumference The diameter of a circular pond is 42 m. What is its circumference? Use Additional Example 4: Application 22 7 for . C = d You know the diameter. C 22 7 42Substitute 22 7 for and 42 for d. C 22 7 42 1 C 22 7 C 132 The circumference of the pond is about 132 m. Write 42 as a fraction. Simplify. Multiply. 9-1 Perimeter and Circumference The diameter of a circular spa is 14 m. What is its circumference? Use Check It Out: Example for . C = d You know the diameter. C 22 7 14Substitute 22 7 for and 14 for d. C 22 7 14 1 C 22 7 C 44 The circumference of the spa is about 44 m. Write 14 as a fraction. Simplify. Multiply. 9-1 Perimeter and Circumference Class work Problems (We Do) (10 Min) Pg (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 (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 (11, 15, 17, 21, 25 odd) 9-1 Perimeter and Circumference Math Journal (5 Min) Venn Diagram - Each student will be given the title/titles 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 topics (will be 2 topics) about what they know about the topics 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 Standard Lesson Quiz Lesson Quizzes Lesson Quiz for Student Response Systems 9-1 Perimeter and Circumference Lesson Quiz Find the perimeter What is the circumference of a circle with a a radius of 8 inches? Use 3.14 for . 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? 36 in. 45 m in. 66 ft 8 m 12 m 9 m 6 m 10 m 8 in. 10 in Use for . 9-1 Perimeter and Circumference 1. Identify the perimeter. A. 10 in. B. 15 in. C. 24 in. D. 48 in. Lesson Quiz for Student Response Systems 6 in. 9-1 Perimeter and Circumference 2. Identify the perimeter. A. 52 m B m C. 165 m D. 330 m Lesson Quiz for Student Response Systems 18 m 8 m 9-1 Perimeter and Circumference 3. What is the circumference of a circle with a radius of 13 in.? Use 3.14 for . A in. B in. C in. D in. Lesson Quiz for Student Response Systems 9-1 Perimeter and Circumference 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 Lesson Quiz for Student Response Systems