Question

cho \(\widehat{AoB}=90^o\)tia Oc nằm giữa OA,OB . Tính \(\widehat{AoC}\)biết \(\frac{1}{4}AoC=\frac{1}{5}CoB\)

Answer 1

Hình bạn tự vẽ

Tia Oc nằm giữa 2 tia OA,OB nên

\(\widehat{AoC}\)\(+\)\(\widehat{CoB}\)\(=\)\(\widehat{AoB}\) \(\left(1\right)\)

=>\(\widehat{Aoc}+\widehat{CoB}\)\(=90^0\)

Theo đề ta có \(\frac{1}{4}AoC=\frac{1}{5}CoB\left(2\right)\)

Từ \(\left(2\right)\) \(\Rightarrow AoC=\frac{4}{5}CoB\)

Thay \(\frac{4}{5}CoB+CoB=90^0\)

\(=\frac{9}{5}CoB=90^0\)

\(CoB=90^0\div\frac{9}{5}=50^0\)