How do you use Heron's formula to determine the area of a triangle with sides of that are 7, 5, and 11 units in length?

$a = 5 , b = 7 , c = 11 , s = \frac{a + b + c}{2} = \frac{23}{2}$. Then Heron's Formula gives an area of $\setminus \sqrt{\left(\frac{23}{2}\right) \left(\frac{13}{2}\right) \left(\frac{9}{2}\right) \left(\frac{1}{2}\right)} = \left(\frac{3}{4}\right) \setminus \sqrt{299}$ square units.
Heron's Formula is $A r e a = \setminus \sqrt{s \left(s - a\right) \left(s - b\right) \left(s - c\right)}$ where a, b, c are the sides and s is half their sum.