Kẻ MF//AB//CDMF//AB//CD
⇒ˆBMF=ˆABM=30°⇒BMF^=ABM^=30° (Hai góc so le trong)
ˆDMF=ˆMDC=60°DMF^=MDC^=60° (Hai góc so le trong)
Ta có:
ˆBMD=ˆBMF+ˆDMF=30°+60°=90°BMD^=BMF^+DMF^=30°+60°=90°
⇒BM⊥DM⇒BM⊥DM
mình làm nhầm nên xóa câu trl rồi, mong cậu thcam ạ