3. A bamboo pole is 24 meters long, one end leaning against a wall, and the other end on the ground. If a certain node on the bamboo pole is 7 meters vertically from the wall and 7 meters vertically from the ground, then the vertical distance from the end of the bamboo pole leaning against the wall to the ground is meters, or $\qquad$ meters.
3. $16 \pm 4 \sqrt{2}$