Câu 5:
AB//CD
AB\(\perp\)AD
Do đó: AD\(\perp\)CD tại D
=>\(\widehat{D_1}=90^0\)
AB//CD
=>\(\widehat{DCB}=\widehat{B_1}\)(hai góc so le trong)
mà \(\widehat{DCB}=130^0\)
nên \(\widehat{B_1}=130^0\)
Câu 2: \(\widehat{xOy}+\widehat{yOz}=180^0\)(hai góc kề bù)
=>\(\widehat{yOz}+70^0=180^0\)
=>\(\widehat{yOz}=180^0-70^0=110^0\)
Câu 1:
Ta có: tia Ay nằm giữa hai tia Ax và Az
=>\(\widehat{xAy}+\widehat{yAz}=\widehat{xAz}\)
=>\(\widehat{yAz}=90^0-40^0=50^0\)