帮忙把第十一题的第二小题和第十二题解出来写在纸上
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/07/19 11:47:03
帮忙把第十一题的第二小题和第十二题解出来写在纸上
![](http://img.wesiedu.com/upload/4/5a/45abca8f654cd4644b6fe9ac5f3b72c4.jpg)
![](http://img.wesiedu.com/upload/4/5a/45abca8f654cd4644b6fe9ac5f3b72c4.jpg)
已知角BGC =180°-1/2(角ABC +角ACB )
又因为角ABC+角ACB +角A=180°
所以角BGC =180°-1/2(180°-角A)
=90°+1/2角A 再答: ��Ϊ�ı����ڽǺ�Ϊ360�� �ҽ�A=��C=90�� ���Խ�B+��D=180�� ����ΪBEƽ�ֽ�B DFƽ�ֽ�D ���Խ�EBC=1/2��B ��FDC=1/2��D ���Խ�EBC +��FDC =1/2(��B+��D) ���Խ�EBC +��FDC=90�� ����Ϊ������ڽǺ�Ϊ180�㣬�ҽ�CΪ90�� ���Խ�DFC+��FDC =90�� ���Խ�EBC =��DFC ����BE//DF
又因为角ABC+角ACB +角A=180°
所以角BGC =180°-1/2(180°-角A)
=90°+1/2角A 再答: ��Ϊ�ı����ڽǺ�Ϊ360�� �ҽ�A=��C=90�� ���Խ�B+��D=180�� ����ΪBEƽ�ֽ�B DFƽ�ֽ�D ���Խ�EBC=1/2��B ��FDC=1/2��D ���Խ�EBC +��FDC =1/2(��B+��D) ���Խ�EBC +��FDC=90�� ����Ϊ������ڽǺ�Ϊ180�㣬�ҽ�CΪ90�� ���Խ�DFC+��FDC =90�� ���Խ�EBC =��DFC ����BE//DF