CIRCLES

1. CIRCLES SPI 3108.3.1 Use algebra and coordinate geometry to analyze and solve problems about geometric figures (including circles). JIM SMITH JCHS

2. DEFINITION A CIRCLE IS A SET OF POINTS EQUIDISTANCE FROM A GIVEN POINT CALLED THE CENTER . ∙

3. PARTS OF A CIRCLE CENTER A Ex. A

4. PARTS OF A CIRCLE RADIUS RADII D B Ex. DA, BA, CA A DISTANCEFROM CENTER TO CIRCLE C

5. PARTS OF A CIRCLE CHORDS B C Ex. BG, CE, DF G ENDPOINTS ARE ON THE CIRCLE D F E

6. PARTS OF A CIRCLE DIAMETER B Ex. BC A CHORD THAT CONTAINS THE CENTER C

7. PARTS OF A CIRCLE B d = 2r r = d / 2 A Ex. BC = 2BA C

8. B DIAMETERS OF CIRCLES A, B, and C ARE 14, 20, and 10 C A X Y FIND XB FIND BY

9. C A X Y B FIND XB XB = AB- AX XB = 10 – 7 XB = 3 FIND BY BY = BC – CY BY = 10 – 5 BY = 5

10. CIRCUMFERENCE C = 2 π r or C = d π • FIND C if r = 7 • C = 2 π 7 • C = 14 π or 43.96 • FIND C if d = 12 • C = 12 π or 37.68

11. 5 5 FIND THE CIRCUMFERENCE EXACT ANSWER NEAREST TENTH

12. 5 5 45,45,90 TRIANGLE d = 5√2 EXACT ANSWER C = 5√2π NEAREST TENTH C = 22.2