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

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

PARTS OF A CIRCLE CENTER A Ex. A

PARTS OF A CIRCLE RADIUSRADII DISTANCE FROM CENTER TO CIRCLE A B C D Ex. DA, BA, CA

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

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

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

DIAMETERS OF CIRCLES A, B, and C ARE 14, 20, and 10 B A XY C FIND XB FIND BY

B A XY C FIND XB XB = AB- AX XB = 10 – 7 XB = 3 FIND BY BY = BC – CY BY = 10 – 5 BY = 5

CIRCUMFERENCE C = 2 π r or C = d π FIND C if r = 7 1) FIND C if r = 7 C = 2 π 7 C = 2 π 7 C = 14 π or C = 14 π or ) FIND C if d = 12 C = 12 π or C = 12 π or 37.68

5 5 FIND THE CIRCUMFERENCE EXACT ANSWER NEAREST TENTH

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