Do they give it to us? Well, look right over here. They say the height of the triangle is increasing at a rate of six meters per hour. So if they're saying h of t is increasing, they're telling us the rate of change of h of t with respect to time, so that's h prime of t, and they're telling us that it is increasing at six meters per hour. So it's gonna be positive six meters per hour. So they did indeed give us that. Now why is all of this a useful exercise to go through?