Answer:
All the options except the third choice are correct.
Explanation:
In the given figure:
[tex]\angle\text{GER}\cong\angle\text{TEA (Vertical Angles)}[/tex]
Since angles G and T are congruent:
• Triangles GER and TEA are similar triangles.
Therefore, the following holds:
[tex]\begin{gathered} \triangle\text{GRE}\sim\triangle\text{TAE} \\ \triangle E\text{GR}\sim\triangle E\text{TA} \\ \frac{GR}{TA}=\frac{RE}{AE} \end{gathered}[/tex]
Similarly:
[tex]\begin{gathered} \frac{EG}{ET}=\frac{GR}{TA} \\ ET=10,EG=5,TA=12,RG=\text{?} \\ \frac{5}{10}=\frac{RG}{12} \\ \frac{1}{2}=\frac{RG}{12} \\ 2RG=12 \\ RG=\frac{12}{2} \\ RG=6 \\ \text{Therefore if }ET=10,EG=5,and\; TA=12,then\; RG=6 \end{gathered}[/tex]
Finally, angles R and A are congruent.
[tex]\begin{gathered} m\angle R=m\angle A \\ 80\degree=(x+20)\degree \\ x=80\degree-20\degree \\ x=60\degree \end{gathered}[/tex]
The correct choices are:
[tex]\begin{gathered} \triangle\text{GRE}\sim\triangle\text{TAE} \\ \triangle E\text{GR}\sim\triangle E\text{TA} \\ \frac{GR}{TA}=\frac{RE}{AE} \\ I\text{f }ET=10,EG=5,and\; TA=12,then\; RG=6 \\ \text{If }m\angle R=80\degree\text{ and }m\angle A=(x+20)\degree,then\; x=60\text{ } \end{gathered}[/tex]
Only the third choice is Incorrect.
