题目

如图所示，△ABC中，∠C=90°，∠B=30°，AD是△ABC的角平分线，若AC=．求线段AD的长．  答案：2解析:解：∵△ABC中，∠C=90º，∠B=30，∴∠BAC=60，        ………………………………………………………1分∵AD是△ABC的角平分线，∴∠CAD=30，    ……………………………………………………………2分∴在Rt△ADC中，    ………………………………………3分=×     ……………………………… This kind of books ________ well, and they ________ in a short time． [　　] A．sell, were sold out B．sells, were sold out C．was sold, sold out D．were sold, sold out