Question

Diketahui jari-jari lingkaran 21 cm dan besar sudut AOB=60 drjat dgn O titik titik pusat serta A dan B di keliling lingkaran. Tentukan :
a. pnjang busur AB
b. Luas juring OAB
c. luas tmbereng AB

Answer 1

A. panjang busur ab = k.lingkaran*</360
                             = 22/7*42*60/360
                             = 22*6*1/6
                             = 22
b. L juring oab = 22/7*21*21*60/360
                     = 22*3*21*1/6
                     = 231
c. L tembereng = L juring - (1/2*at)
                       = 231 - (1/2*21*10,5√3)
                       = 231 - 110,25√3

Answer 2

 a. 60/360 = Pb AB/2πr
= 1/6 = Pb AB/2x22/7x21
= 1/6 = Pb AB/132
= 6xPb AB = 1x132
= Pb AB = 1x132:6
=Panjang busur AB = 22

b. 60/360 = Lj AOB/πr²
= 1/6 = Lj AOB/22/7x21x21
=1/6 = Lj AOB/1386
=6xLj AOB = 1x1386
=Lj AOB =1x1386:6
=Luas juring AOB = 231