The outside of the circle is calledcircumferenceThe circumference is the distance around the circle.The midpoint of a circle iscentreThe line drawn from the centre to the circumferenceis radiusThe line drawn from one circumference through the centre to another circumference is radiusdiameterThe diameter cuts the circle in half!A line that connects one point on the edge of the circle with another point on the circle is called .chordThe chord that passes through thecentre of the circle is the diameter.A segment ie. part of the circumference of the circle is called an ...arcSectorArcA sector is the part of a circle between two radii and an arcAn arc is the part of the circumference at the edge of a sectorSegmentTangentA segment is the part of a circle between a chord and an arcA tangent is a straight line which touches a circle at one point onlyParts of the CirclecentreradiusdiameterchordarcThe circumference and Area of a circleDiameterRadiuscentreWhat is the formula relating the circumference to the diameter?People knew that the circumference is about 3 times the diameter but they wanted to fnd out exactly. C = ? x dC! x dThis means A""R#$%&AT'() '*+A( T#The exact true alue is+,-,#W,..An approximation to !!"3.#$#%&'(%3%)&*&3'3)$('($33)3'*&%+'))$#&*#(&3&&3*%#+%)'+&*$&$$%&'3+*)#($+(')('+)&&)(')+3$)'%3$'##*+(*&)'#$)+)(%#3')'3+(($*+&3)$$(+&%%+%)''3#*'%3%&$+)#')$)###*$%+')$#+'*+#&3)%'##+%%%&($$(''&$)&%$&3+3)#&($$'))#+&*%((%&33$$(#')$*%($)'33*)(*)3#(%'*#'+#&+$%($)%((&'3$(+3$)(#+$%$3'(($)'#33&3(+*'(+'$$#'*3*'$%)*++((+(3#%%))#*$))#%'+&'+&(')'&'%$+*#%3($3(*)&'%&+3(++##33+%3+%$))'+$((%'#3)$#$(&%#&$#%##(+&................foreer. ,hat about the A-.A of a circle//r/rr0irst consider a s1uareThe area of this s1uare in terms of r isA= /r x/r = 2r/,hat about the A-.A of a circle//r/r,ow consider a circle inside the s1uareThe area of the circle must be less than the are of the s1uareA32r/rArea=? xr/0inding a formula for the area of a circleC= 4d orC=/4rSemi5circle=4r4rrArea of Rectangle= 6ase x 7eightArea = 4r x rArea =4r/The Area and Perimeter of a CircleA circle is defined by its diameter or radiusDiameterradiusThe perimeter or circumference of a circle is the distance around the outsideThe area of a circle is the space inside itThe ratio of4 8pi9=diameternce circumfere is an irrational number whose value to 15 decimal places is = 3.14159265358979....e usuall! sa! "3.14The circumference is found using the formulaC=4 dor C= /4r8since d=/r9The area is found using the formulaA=4r/The Area and Perimeter of a CircleA circle is defined by its diameter or radiusDiameterradiusThe perimeter or circumference of a circle is the distance around the outsideThe area of a circle is the space inside itThe ratio of4 8pi9=diameternce circumfere is an irrational number whose value to 15 decimal places is = 3.14159265358979....e usuall! sa! "3.14The circumference is found using the formulaC=4 dor C= /4r8since d=/r9The area is found using the formulaC=4r/