如图，在直角三角形ABC中，∠ACB=90°，AC=BC=10，将△ABC绕点B沿顺时针方向旋转90°得到△A1BC1．（1）线段A1C1的长度是 ，∠CBA1的度数是 ．（2）连结CC1，求证：四边形CBA1C1是平行四边形．
直接写得数． += += += 1﹣= 1﹣﹣= 7﹣=
怎样算简便就怎样算．++ +++ ﹣（+）
直接写出得数．+= ﹣= += ﹣=1﹣= += ﹣= +=
直接写出得数．= = = == = = =
直接写出得数．= = == = == = == = =
+
= 
+
= 
+
= 1﹣
= 1﹣
﹣
= 7﹣
=
+
+
+
+
+
﹣（
+
）
+
= 
﹣
+
= 
﹣
=
= 
+
= 
﹣
= 
+
=
= 
= 
= 
=
= 
= 
= 
=
= 
= 
=
= 
= 
=
= 
= 
=
= 
= 
=
粤公网安备 44130202000953号