It is given that the plate is a square.
Therefore, let us represent the side of the square by the variable, "a".
Therefore, it is given to us that:
inches.
Now, we have to find the diagonal of the square. We know that the diagonal,
of a square is given by the formula:

Applying the above formula to our case we get the diagonal to be as:
inches.
Therefore, the length of the diagonal to the nearest tenth of an inch is:
inches.