the short and long hands of a clock are 8cm and 12 cm respectively find the sum of distances travelled by their tips in 60 hours

Hi! :D

Length of short hand = 8cm Let us consider it as r = 8cm.
Distance traveled by short hand in 1 hour = 2​​π​r = 2​π8 = 16​πcm
Hence distance traveled by its tip in 60 hrs = 16​π x 60 = 960​πcm.
 
Length of minute hand = 12cm
Distance traveled by its tip in a minute = 2​π12 = 24π
Hence distance traveled by it in 60 hours = 60 x 60 = 3600 minutes = 24​πx3600 =                                                                                                                          86400​πcm
Sum of their distances = (960 + 86400)​π = 87360πcm = 87360 x 22/7 = 274560cm
                                                            = 2745.6m = 2.7456km = 2.7km (approx.)

Hope this helps! :)