Bài 7:
Ta có:
\(\widehat{xOy}+\widehat{yOz}=\widehat{xOz}=150^o=>\widehat{xOy}=150^o-\widehat{yOz}\)
Mà: \(\widehat{xOy}-\widehat{yOz}=90^o=>150^o-\widehat{yOz}-\widehat{yOz}=90^o\)
\(=>2\widehat{yOz}=150^o-90^o=60^o\\ =>\widehat{yOz}=\dfrac{60^o}{2}=30^o\\ =>\widehat{xOy}=150^o-30^o=120^o\\ \widehat{xOz'}=180^o-120^o-30^o=30^o\\ =>\widehat{x'Oy}=\widehat{yOz}+\widehat{x'Oz}=30^o+30^o=60^o\)
Câu 3:
a:
b:
c:
Câu 6:
Ta có: \(\widehat{AOC}+\widehat{COD}+\widehat{BOD}=180^0\)
=>\(\widehat{COD}+10^0+80^0=180^0\)
=>\(\widehat{COD}=180^0-90^0=90^0\)
=>\(\widehat{COD}\) là góc vuông