题目

如图，把△ABC绕点C顺时针旋转36°得到△A′B′C，A′B′交AC于点D，若∠A′DC=900，则∠A度数为（ ）A. 44° B. 54° C. 36° D. 76° 答案：【答案】B【解析】先根据旋转的性质得∠ACA′=36°，∠A=∠A′，则利用互余计算出∠A′=54°，从而可得到∠A的度数．解：∵△ABC绕点C按顺时针的方向旋转36°，得到△A'B'C，∴∠ACA′=36°，∠A=∠A′，∵∠A′DC=90°，∴∠A′=90°-36°=54°，∴∠A=54°．故选：B．You were supposed ________ to the teacher's office. A. to go B. goes C. going D. went