1: Ta có: \(\hat{ABP}=\hat{ABC}+\hat{CBP}=90^0+\hat{CBP}\)
\(\hat{MBC}=\hat{MBP}+\hat{CBP}=90^0+\hat{CBP}\)
Do đó: \(\hat{ABP}=\hat{BMC}\)
Xét ΔABP và ΔMBC có
BA=BM
\(\hat{ABP}=\hat{MBC}\)
BP=BC
Do đó; ΔABP=ΔMBC
Ta có: \(\hat{CBP}+\hat{C^{\prime}BP}=\hat{CBC^{\prime}}=90^0\)
\(\hat{C^{\prime}BM}+\hat{C^{\prime}BP}=\hat{MBP}=90^0\)
Do đó: \(\hat{CBP}=\hat{C^{\prime}BM}\)
Xét ΔCBP và ΔC'BM có
CB=C'B
\(\hat{CBP}=\hat{C^{\prime}BM}\)
BP=BM
Do đó: ΔCBP=ΔC'BM

