And we know what this bottom side of this right triangle is. This altitude splits this side exactly into two. So this right over here has length s over 2. So to figure out what h is, we can just use the Pythagorean theorem. We would have h squared plus s over 2 squared is going to be equal to the hypotenuse squared. It is going to be equal to s squared. So you would get h squared plus s squared over 4 is equal to s squared.