Answer:
The best approximation of AB is 2 meters.
Explanation:
Notice that this situation models a right triangle, when the height, which is a leg of the triangle, is 6 meters.
Also, we know the angle between the ladder and the ground, which is 72°.
To find the distance from A to B, which from the bottom of the ladder to the bottom of the wall, we just need to use trigonometric reasons.

Why we use tangent? Because it relates both legs where we just need to find the adjacent one.

Therefore, the best approximation of AB is 2 meters.