Question

Answer 1

4\(\):

\(\widehat{xOy}+\widehat{yOz}=180^0\)(hai góc kề bù)

=>\(\widehat{yOz}+25^0=180^0\)

=>\(\widehat{yOz}=155^0\)

5:

\(\widehat{AOB};\widehat{BOC}\) là hai góc kề nhau

=>OB nằm giữa OA và OC

=>\(\widehat{AOB}+\widehat{BOC}=\widehat{AOC}\)

\(\widehat{AOB}=\dfrac{1}{5}\cdot\widehat{AOC}\)

=>\(\widehat{AOB}=\dfrac{1}{5}\cdot80=16^0\)

\(\widehat{AOB}+\widehat{BOC}=\widehat{AOC}\)

=>\(\widehat{BOC}+16^0=80^0\)

=>\(\widehat{BOC}=64^0\)