Provide the missing information.

Given a triangle of sides of lengths $a,b,$ and $c,$ Heron's formula gives the area of the triangle as Area $\sqrt[\phantom{2}]{s(s-a)(s-b)(s-c)},$ where $s$ represents half the perimeter of the triangle. That is $s=$

Select one:

a$.\frac{1}{2}(a+b+c)$

b$.\frac{2}{1}(a+b+c)$

c$.\frac{1}{3}(a+b+c)$

d$.\frac{1}{4}(a+b+c)$