HW: p.345(9-11), p.347(18-20) Materials Thursday, 3/23/17 Write the IC and HW in your planner. IC: Ch. 8 Circles – day 5 HW: p.345(9-11), p.347(18-20) Show all work! Materials Pencil & grading pen Slate/marker/eraser Math folder HW due today (Circumference & Area #2) 1 1 1 1 1

The circumference of a regulation NCAA men’s basketball must be 29 The circumference of a regulation NCAA men’s basketball must be 29.987 inches. What would be the diameter of the basketball?

Bell-Work Mystery Comic x In Timothy’s book collection, he has 5 science fiction books, 6 comic books, and 4 mystery books. During the fourth quarter, Timothy wants to pick two books to read. What is the probability of him choosing a mystery book and then a comic book ? (Being the typical 7th grader, he picked the 1st book, chucked it on his floor, and then picked the 2nd book.) 1st Pick 2nd Pick Mystery Comic         x  

Bell-Work Blue Red x 1st Pick 2nd Pick A bag of marbles contains 3 red, 4 blue, and 7 green marbles. With replacement, what is the probability of selecting a blue marble and then a red marble? 1st Pick 2nd Pick Blue Red         x  

"...in terms of pi" 9 in = r 9 in 18 in = d Ch. 8.1 & 8.3 - State Standard 7.G.4 Objective: TSWBAT discover the other area formula for circles and leave answers in terms of pi. Date ______________________ "...in terms of pi" Example 1: What is the circumference of a circle with a radius of 9 inches? Write your answer in terms of pi. C =  d 9 in = r C =  (18) 9 in 18 in = d C = 18  inches

"...in terms of pi" 6 in = d 6 in 3 in = r Example 2: What is the area of a circle with a diameter of 6 inches? Use 3.14 for pi. 6 in = d A = ½ C  r 6 in 3 in = r

d = 2 d =6 d = 14 d = 20 r = 1 r = 3 r = 7 r = 10 radius C = d diameter d = 2 d =6 d = 14 d = 20 radius C = d A = ½C•r r = 1 r = 3 r = 7 r = 10 C = 2 C = 6 C = 14 C = 20 C = •2 14 20 6 ½ (2)•1 ½ (6)•3 ½ (14)•7 ½(20)•10 1 • 1 3 • 3 7 • 7 10 • 10 A = 1 A = 9 A = 49 A = 100 A = r² •  = r² Shortcut formula for area: ________________

"...in terms of pi" 6 in = d 6 in 3 in = r Example 2: What is the area of a circle with a diameter of 6 inches? Write your answer in terms of pi. 6 in = d A =  r² 6 in A =  (3²) 3 in = r A = 9  A = 9  in²

Find the area in terms of pi: Now it's time for... SLATES! Slates 1: 16 ft Find the circumference a) in terms of pi and b) using 3.14 for pi. a) C = 16 ft b) C ≈ 50.24 ft Slates 2: 5 in. Find the area in terms of pi: A = 25 in²

Slates again! Woo-hoo! Slates 1: A circular swimming pool has a diameter of 10 meters. How much area of the backyard does the pool cover? Area or Circumference? Draw a picture: Slates 2: The circular lid for a jar has a radius of 4 centimeters. What is the circumference of the lid? Area or Circumference? Draw a picture:

Closure A seventh grade student completed this math problem: On your slate, identify what the student’s mistake was in finding the area of the circle.

p.345 p.347