The variable a is the length of the ladder. The variable h is the height of the ladder's top at time t, and x is the distance from the wall to the ladder's bottom. Suppose that the length of the ladder is 7.7 meters and the top is sliding down the wall at a rate of 0.2 m/s. Calculated when h = 2.9. (Use decimal notation. Give your answer to three decimal places.) h