ForAX​=−B and C=2B=Bcos2ωt+Bsin2ωt=2​Bsin(2ωt+4π​)​This is equation of SHM of amplitude 2​B.If A=B and C=2B, then X=B+Bsin2ωtThis is also equation of SHM about the point X=B.Function oscillates between X=0 and X=2B with amplitude B