Step 1:
Draw the rectangle with the given dimensions
Step 2:
Next, apply the Pythagoras theorem
Opposite = 12
Adjacent = 18
Hypotenuse = L the side facing right angle
Step 3:
[tex]\begin{gathered} \text{Pythagoras theorem} \\ \text{Opposite}^2+Adjacent^2=Hypotenuse^2 \\ 12^2+18^2=L^2 \\ 144+324=L^2 \\ 468=L^2 \\ L\text{ = }\sqrt[]{468} \\ \text{L = 6}\sqrt[]{13} \\ L\text{ = 21.6'} \end{gathered}[/tex]
Final answer
The length of the diagonal is 21.6
