设函数f（u）连续，区域D＝{（x，y）|x^2＋y^2≤2y}，则<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23819722_0.png">等于（　　）。<br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23819722_0_1.png">