If we were to drop an altitude just like this, this length right over here, this is the height. And this would be perpendicular just like that. So our area is going to be equal to 1 half times our base is s, 1 half times s times whatever our height is. Now, how can we express h as a function of s? Well, to do that, we just have to remind ourselves that what we've drawn over here is a right triangle. It's the left half of this equilateral triangle. And we know what this bottom side of this right triangle is.