1. Area and Circumference 5-4-09 IMP3 Sia

2. Today’s Agenda  Bell ringer, seating chart  Collect take-home quizzes  Go over HW  Area and circumference formulas for circles  HW16 p. 105 (in green book) due Friday, May 8th

3. Announcements  ACT session on Saturday, May 30th in room 208 from 8am-10am  HW16 p. 105 from green book is due Friday, May 8th  HW Hall this Thursday during 9th period (not Tuesday)  Return your graphing calculator to Ms. Sia by this Friday, May 8th  # of students who completed last week’s HW:  3 rd period: 6 out of 24 (25%)  4 th period: 4 out of 17 (24%)  5 th period: 3 out of 17 (18%)

4. Remember…  HW is due at the end of every week.  Quizzes will be during class every Friday.  You are to sit in your assigned seat.  All necessary information to complete class work is in your notes or geometry packets.

5. Orchard Hideout  Last week, you needed to read p. 60-61 to know what the unit is about.  We’re not doing all of the unit, but several HW assignments are from the unit.  This week: Use area and circumference formulas to answer problems on HW16 p. 105

6. This week’s vocabulary  Circle  Center  Radius  Area  Circumference  Arc  Sector  360°

7. Area of Circles  Area describes the amount of space an object takes up.  For circles, to find its area, take the radius, square it, then multiply by pi.

8. Circumference  Circumference describes the distance around a circle.  Circumference is simply the perimeter of a circle.

9. Arc  An arc has two points on a circle and all the points of the circle needed to connect those two points.  We say “arc AB”

10. Sector  A sector of a circle is a region bounded by two radii and an arc of a circle.

11. Exact vs. Approximate  Example: Find the circumference of a circle with radius 7. EXACT: C = 2  r = 2  (7) = 14  APPROXIMATE: C = 2  r = 2  (7) = 14  = 43.98 I will let you know whether I want exact or approximate answers for your class work. For this week’s HW, use EXACT ANSWERS.