hitunglah beserta caranya!

1/2 keliling gir belakang = 1/2 π d
                                      = 1/2 x 3,14 x 15
                                      = 23,55, cm

1/2 keliling gir depan = 1/2 π d
                                  = 1/2 x 3,14 x 10
                                  = 15,7 cm

taksiran panjang rantai =  23,55 + 15,7 + (2 x 70)
                                     =  23,55 + 15,7 + 140
                                     = 179,25 cm