Given the following relationships between the symbols:
$$\square >◯\text{and}◯=\Delta$$

Which of the following options is definitely true?

Let's combine the given relationships into a single mathematical chain:
$$\square >◯=\Delta$$

Now let's evaluate each option based on this chain:

*Option A ($\square >\Delta$):** Since $\square >◯$ and $◯=\Delta$, it directly implies that $\square >\Delta$. This statement is definitely true.
*Option B ($◯>\Delta$):** This contradicts the given condition $◯=\Delta$, so it is false.
*Option C ($\Delta =\square$):** Since $\square$ is strictly greater than $\Delta$, they cannot be equal. This is false.
*Option D ($\Delta >\square$):** This is the exact opposite of $\square >\Delta$, so it is false.

Therefore, Option A is the only definitely true statement.