Đáp án:
$\Delta I'E'F'$
Giải thích các bước giải:
$\begin{array}{l}
{V_{\left( {B,\frac{1}{2}} \right)}}\left( D \right) = I\,voi\,\overrightarrow {BI} = \frac{1}{2}\overrightarrow {BD} \\
{V_{\left( {B,\frac{1}{2}} \right)}}\left( I \right) = E\,voi\,\overrightarrow {BE} = \frac{1}{2}\overrightarrow {BI} \\
{V_{\left( {B,\frac{1}{2}} \right)}}\left( C \right) = F\,voi\,\overrightarrow {BF} = \frac{1}{2}\overrightarrow {BC} \\
\Rightarrow {V_{\left( {B,\frac{1}{2}} \right)}}\left( {\Delta DIC} \right) = \Delta IEF\\
{T_{\overrightarrow {CB} }}\left( I \right) = I'\,voi\,\overrightarrow {II'} = \overrightarrow {CB} \\
{T_{\overrightarrow {CB} }}\left( E \right) = E'\,voi\,\overrightarrow {EE'} = \overrightarrow {CB} \\
{T_{\overrightarrow {CB} }}\left( F \right) = F'\,voi\,\overrightarrow {FF'} = \overrightarrow {CB} \\
\Rightarrow {T_{\overrightarrow {CB} }}\left( {\Delta IEF} \right) = \Delta I'E'F'
\end{array}$
