예를 들어, AC CB, BD CB, AB=DC, 검증 ABD=☞ACD

예를 들어, AC CB, BD CB, AB=DC, 검증 ABD=☞ACD

증명:
✔️AC∙CB, BD ΔCB
☞ ACB=☞DBC=90°
▷AB=DC, BC=CB
ABC, DCB
☞DCB=☞ABC
☞ ACB=☞DBC=90°
ABD=☞ACD