In this subunit, we will make use of another concept that you have known and understood for quite some time: the distance formula. If you want to estimate the length of a curve on a certain interval, you can simply calculate the distance between the initial point and terminal point using the traditional formula. If you want to increase the accuracy of this measurement, you can identify a third point in the middle and calculate the sum of the two resulting distances. As we add more points to the formula, our accuracy increases: the exact length of the curve will be the sum (i.e. the integral) of the infinitesimally small distances.