A model-dependent amplitude analysis of B±DK± with DKS0+ decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 1 fb1, recorded by LHCb at a centre-of-mass energy of 7 TeV in 2011. Values of the CP violation observables x± and y±, which are sensitive to the CKM angle , are measured to bex=+0.027±0.0440.008+0.010±0.001,y=+0.013±0.0480.007+0.009±0.003,x+=0.084±0.045±0.009±0.005,y+=0.032±0.0480.009+0.010±0.008, where the first uncertainty is statistical, the second systematic and the third arises from the uncertainty of the DKS0+ amplitude model. The value of is determined to be (8442+49)°, including all sources of uncertainty. Neutral D meson mixing is found to have negligible effect.
