To simplify the expression \(-(-1.2)^2\), we first need to calculate \((-1.2)^2\).
Calculating \((-1.2)^2\): \[ (-1.2) \times (-1.2) = 1.44 \]
Now, we apply the negative sign in front of the squared value: \[ -(-1.2)^2 = -1.44 \]
Since there is another negative sign in front of this result, we have: \[ -(-1.44) = 1.44 \]
Thus, the simplified expression is: \[ \boxed{1.44} \]