Bài 6:
a, Ta có: xy//BC(gt)
=> \(\widehat{xAB}=\widehat{B}=50^{o}\)
=> \(\widehat{yAC}=\widehat{C}=40^{o}\)
b, Lại có: \(\widehat{BAC}+\widehat{B}+\widehat{C}=180^{o} \)
\(\widehat{BAC}+50^{o}+40^{o}=180^{o}\)
\(\widehat{BAC}+90^{o}=180^{o} \)
\(\widehat{BAC} =90^{o}\)
c,Xét AHC vuông tại H có:\(\widehat{HAC}+\widehat{C}=90^{o} \)
\(\widehat{HAC}+ 40^{o}=90^{o}\)
\(\widehat{HAC}=50^{o}\)
Nếu thấy hay và đúng thì cho mik xin 1 like+1 follow nha
cảm ơn bn