Question

làm dùng em với

 

Answer 1

\(a,\left\{{}\begin{matrix}a\perp AB\\a//b\end{matrix}\right.\Rightarrow b\perp AB\\ b,a//b\Rightarrow\widehat{D}+\widehat{C}=180^0\left(trong.cùng.phía\right)\\ \Rightarrow\widehat{D}=180^0-120^0=60^0\)

\(c,\) Vì CI là p/g \(\widehat{ACD}\) nên \(\widehat{DCI}=\dfrac{1}{2}\widehat{ACD}=60^0\)

Xét tg CDI có \(\widehat{D}+\widehat{DCI}+\widehat{CID}=180^0\)

\(\Rightarrow\widehat{CID}=180^0-60^0-60^0=60^0\)