S=1/2*6*6

To calculate \( S \) using the formula you've provided, where \( S = \frac{1}{2} \times 6 \times 6 \):

\[ S = \frac{1}{2} \times 6 \times 6 \] \[ S = \frac{1}{2} \times 36 \] \[ S = \frac{36}{2} \] \[ S = 18 \]

So, \( S = 18 \).