\(\widehat{C}+\widehat{A}=180^0-60^0=120^0\)
mà \(\widehat{C}< \widehat{A}\)
nên \(\widehat{C}< 60^0;\widehat{A}>60^0\)
Xét ΔABC có \(\widehat{C}< \widehat{B}< \widehat{A}\)
nên AB<AC<BC
Xét `△ABC` có:
\(\widehat{B}=60^0\)
mà \(\widehat{C}< \widehat{A}\)
nên
\(\widehat{A}+\widehat{C}=180^0-\widehat{B}\)
\(\widehat{A}+\widehat{C}=180^0-60^0\)
\(\widehat{A}+\widehat{C}=120^0\)
Mà: \(\widehat{C}< \widehat{A}\)
`=>` \(60^0< \widehat{A}< 120^0\)
\(\widehat{C}< 60^0\)
Trong `△ABC` có:
\(\widehat{C}< \widehat{B}< \widehat{A}\)
`=> AB < AC < BC`