ans fast ???? Share with your friends Share 0 Anuradha Sharma answered this Dear Student, Now since a1a2,b1b2,c1c2 are in AP. So Let A-D, A, A+D are these terms so a1=a2A-Db1=b2Ac1=c2A+DNow put this in the above condition and simlipfy to get the desired result. Regards -2 View Full Answer