CIRCLES Arc Length, Sectors, Sections
Circumference C = 2πr C = 2π7 C = 14π 7
area A = πr² A = π9² A = 81π 9
A B ARC LENGTH The length of AB represents a fractional part of the circle’s circumference. If the mAB Is 90°, then the length of AB is 90/360th (1/4th) of the circumference.
C = 2 π r C = 2 π 6 C = 12π Find the length of AB 90/360 = ¼ Length of AB = ¼·12π = 3π
C = 2πr C = 16π AB = 60/360 of 16π AB = 1/6 · 16π AB = 1 · 16π 6 1 60° A B AB = 60/360 of 16π AB = 1/6 · 16π AB = 1 · 16π 6 1 AB = 8π 3 8
Find the length of XYZ C = 2πr C = 18π XYZ = 240 of 18π 360 120° Find the length of XYZ 9 C = 2πr C = 18π XYZ = 240 of 18π 360 XYZ = 2 · 18π 3 1 XYZ = 12π 360° - 120° 240°
Sectors are a fractional part of a circle’s area Area of sectors Sectors are a fractional part of a circle’s area
Sector area = ¼ of 64π 64π = 16π 4 Find the shaded area A = πr² A = 64π 8 Sector area = ¼ of 64π 64π = 16π 4 90 of circle’s area 360
A = 1 of 144π 6 144π = 24π Area = πr² A = 144π Sector area = 60° 12 60 of circle’s area 360