Let's just assume that we're drawing it at that moment, t sub zero, because I think that's going to be important. Y at t sub zero is equal to 15 meters. They want to know what is the rate of change of the angle theta between the ground and the ladder. This is the same. Theta is also going to change with respect to time. It's going to be a function of time between the ground and the ladder at that instant. Theta, let me get a new color here.