1. By: Shirley Tung and Abbey Burke

2.  In this section: Understand and apply the principle of CPCTC Recognize basic information about circles.

4.  After getting two triangles congruent to each other, getting corresponding parts congruent is simple. All you need is CPCTC. A BC D E F

5. .O All circles are named by their centers. Every point on a circle is the same distance from its center. Points A and B are on circle O. Theorem 19- All radii of a circle are congruent ^ this circle would be named: Circle O A B

6.  The circumference of a circle is the distance around the outside of it. The formula for finding the circumference is… A C Knowing that the length of is 8, we can use that information to find the circumference of circle A. 8

7.  The area of a circle is the amount of space inside of it. The formula to find the area of a circle is… *NOTE if the exact answer is needed, press the button on the calculator. If an estimated answer is needed, type in 3.14. B C Knowing that the length of is 6, we can find the area using the area formula. 6

8.  Sample problem AB CD E Given: Circle E Conclusion:

9.  Sample problem answer: A B C D E Given: Circle E Conclusion: Statements Reasons 1.Circle E 1.Given 2. 2. All radii of a circle are 3. 3. same as 3 4. 4. vertical angles are 5. 5. SAS (2,3,4) 6. 6. CPCTC

10.  Problem #1 F R O G Given: Circle O Prove:

11.  Problem #1 answer: F R O G Given: Circle O Conclusion: ReasonsStatements 1.Circle O 1. Given 2. 2. Given 3. are rt. angles 3. lines form rt. Angles 4. 4. rt. Angles are congruent 5. 5. all radii of a circle are congruent 6. 6. Reflexive 7. 7. SAS (4,5,6) 8. 8. CPCTC

12.  Problem #2: P O R K Y Given: Conclusion:

13.  Problem #2 answer: P O R K Y Given: Conclusion: StatementsReasons 1. 1. Given 2. 2. Given 3. 3. reflexive 4. 4. SAS (1,2,3) 5. 5. CPCTC

14.  Sample Problem.R 11 Find the area and circumference of circle R to the nearest tenth.

15.  Sample Problem answer:.R 11

16.  Practice Problem.M 9 Find the exact area and circumference of circle M.

17.  Practice Problem answer:.M 9

18.  Rhoad, Richard. Geometry For Your Enjoyment. New ed. Illinois: McDougal Littell, 1991. 125-30. Print.