Find the determinant of the following 3x3 matrix: \[ A = \begin{bmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{bmatrix} \]

Step 1 ：First, we can use the formula for the determinant of a 3x3 matrix: \( det(A) = aei + bfg + cdh - ceg - bdi - afh \) where a, b, c, d, e, f, g, h, i are the elements of the matrix.

Step 2 ：Substitute the elements of the matrix into the formula: \( det(A) = (1*5*9) + (2*6*7) + (3*4*8) - (3*5*7) - (2*4*9) - (1*6*8) \)

Step 3 ：Calculate the above expression: \( det(A) = 45 + 84 + 96 - 105 - 72 - 48 \)

Step 4 ：Simplify the above expression to get the final answer: \( det(A) = 0 \)