a) \(AA'C'C\) là hình chữ nhật
\(\left. \begin{array}{l} \Rightarrow AC\parallel A'C'\\A'C' \subset \left( {A'C'B} \right)\end{array} \right\} \Rightarrow AC\parallel \left( {A'C'B} \right)\)
\(ABC'D'\) là hình bình hành
\(\left. \begin{array}{l} \Rightarrow AD'\parallel BC'\\BC' \subset \left( {A'C'B} \right)\end{array} \right\} \Rightarrow AD'\parallel \left( {A'C'B} \right)\)
Ta có:
\(\left. \begin{array}{l}AC\parallel \left( {A'C'B} \right)\\AD'\parallel \left( {A'C'B} \right)\\AC,A{\rm{D}}' \subset \left( {AC{\rm{D}}'} \right)\end{array} \right\} \Rightarrow \left( {AC{\rm{D}}'} \right)\parallel \left( {A'C'B} \right) \Rightarrow \left( {\left( {AC{\rm{D}}'} \right),\left( {A'C'B} \right)} \right) = {0^ \circ }\)
b) Ta có:
\(\left. \begin{array}{l}AB\parallel A'B'\\A'B' \subset \left( {A'B'C'D'} \right)\end{array} \right\} \Rightarrow AB\parallel \left( {A'B'C'D'} \right) \Rightarrow \left( {AB,\left( {A'B'C'D'} \right)} \right) = {0^ \circ }\)
