填空题 <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20240620/14288021_0.png"><br/> ，其中D是由<br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20240620/14288021_0_1.png"><br/> 及x轴所围成的平面区域．