Answer:
Quadrilateral
Step-by-step explanation:
In the sandbox, opposite sides are equal.
However, using Pythagoras Theorem
[tex]14^2\neq 12^2+8^2\\196 \neq 208[/tex]
Therefore, the sandbox cannot be a rectangle since if it were, each triangle must be a right triangle.
In the triangle
Since [tex]198<208[/tex], Angles C and X are acute angles.
Therefore, the sandbox does not satisfy the properties of any known quadrilateral. It is simply a quadrilateral-shaped sandbox.