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這是圖我作了輔助線證明:在AB上取AF=AC∵AE平分角BAC∴角BAE=角EAC AF=AC AE=AE∴△AFE≌△AEC∴角AFE=角C設角EAD為x∵AD垂直BC∴角AED=90-x角AEF=角AED=90-x∴角FEB=180-2(90-x)=2x∵角B+角FEB=角AF…
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