@The-Darkin-Blade Hi again! The variable $$s$$ is there just to make the expression look a little bit cleaner and to make Heron's Formula easier to memorize. See, $$s$$ is just half of the triangle's perimeter, or the semiperimeter: $$s = \frac{ a + b + c}{2}$$ If we tried to remember Heron's Formula only in terms of $$a, b,$$ and $$c,$$ (without $$s$$), the expression would look a lot more ugly. It would look like this: $$\sqrt{(\frac{a + b + c}{2} )(\frac{-a + b + c}{2} )(\frac{a - b + c}{2} )(\frac{a + b -c }{2}}$$ There's another nice thing about $$s$$: since it is equal to the perimeter divided by $$2,$$ it takes us a long way toward the area formula for a triangle. Remember the area formula is $$\frac{1}{2} \times \text{ base } \times \text{ height}$$ So all you have to do to get the area of the triangle is take $$s$$ and multiply it to the sum of the heights of each triangle!