I took this today and just want to know how to do it next time I get a problem like this

In the given figure,
In triangle DEF,
[tex]\tan 45^{\circ}=\frac{12}{EF}\Rightarrow EF=12[/tex][tex]\sin 45^{\circ}=\frac{12}{DF}\Rightarrow\frac{1}{\sqrt[]{2}}=\frac{12}{DF}=DF=12\sqrt[]{2}[/tex]The length of DF is
[tex]12\sqrt[]{2}[/tex]Now in triangle DFG,
[tex]\tan 45^{\circ}=\frac{DF}{FG}=\frac{12\sqrt[]{2}}{FG}[/tex][tex]FG=12\sqrt[]{2}[/tex]The length of FG is
[tex]12\sqrt[]{2}[/tex]Now apply Pythagoras theorem to determine DG,
[tex]DG^2=(12\sqrt[]{2})^2+(12\sqrt[]{2})^2[/tex][tex]DG^2=288+288=576[/tex][tex]DG=\sqrt[]{576}=24[/tex]The length of DG is 24.