To simplify the expression \(\frac{3}{3^2}\), we first evaluate \(3^2\).
\[ 3^2 = 3 \times 3 = 9 \]
So, the expression becomes:
\[ \frac{3}{9} \]
Next, we can simplify \(\frac{3}{9}\) by dividing both the numerator and the denominator by 3:
\[ \frac{3 \div 3}{9 \div 3} = \frac{1}{3} \]
Therefore, the expression \(\frac{3}{3^2}\) simplifies to:
\[ \frac{1}{3} \]
Thus, the equivalent expression is:
\(\frac{1}{3}\)