Statement 3:
[tex]TV\cong XW[/tex]
Reason: Law of cosines
Statement 4:
[tex]VY\cong WY[/tex]
Reason: Law of cosines
Proof
We have the following situation:
Because the law of cosines,
[tex]\begin{gathered} a^2=c^2+d^2-2cd\cos (b) \\ a^2=e^2+f^2-2ef\cos (b) \end{gathered}[/tex]
Therefore,
[tex]c^2+d^2-2cd\cos (b)=e^2+f^2-2ef\cos (b)[/tex]
