A:played
B:playing
C:to play
D:having played
____
在直角坐标系xOy中,以O为极点,x轴正半轴为极轴建立坐标系,曲线C1极坐标方程为ρsin(θ+ π4 )= 22 a,曲线C2参数方程为 {x=−1+cosθy=−1+sinθ (θ为参数).
(Ⅰ)求C1的直角坐标方程;
(Ⅱ)当C1与C2有两个公共点时,求实数a取值范围.