CABPC的精选

问题详情：如图7-22,已知PA平分∠CAB,PC平分∠ACD,AB∥CD.求*:AP⊥PC.图7-22【回答】*：∵PA平分∠CAB，PC平分∠ACD,∴∠PAC=∠CAB，∠PCA=∠ACD,∴∠PAC+∠PCA=∠CAB+∠ACD=(∠CAB+∠ACD).∵AB∥CD,∴∠CAB+∠ACD=180°.∴...