Angle Distance Tree
1. **Problem statement:** Alice observes an object at the top of a tree 4 meters away from the tree base (Point A). She then moves 2 meters closer (Point B), and the tree height is 6 meters. We need to find angles at points A and B to the top of the tree, name these angles, compare their sizes, and find the distances from the object to points A and B.
2. **Define variables and picture:**
- Tree height $h = 6$ m
- Distance from Point A to tree base $d_A = 4$ m
- Distance from Point B to tree base $d_B = 4 - 2 = 2$ m
3. **(i) Find angles at points A and B relative to top of tree:**
These are angles of elevation — angles formed by looking up from ground points A and B to the top of the tree.
Angle at A, $\theta_A = \tan^{-1}(\frac{h}{d_A}) = \tan^{-1}\left(\frac{6}{4}\right)$
Angle at B, $\theta_B = \tan^{-1}(\frac{h}{d_B}) = \tan^{-1}\left(\frac{6}{2}\right)$
Calculate exact values:
$$
\theta_A = \tan^{-1}(1.5) \approx 56.31^\circ
$$
$$
\theta_B = \tan^{-1}(3) \approx 71.57^\circ
$$
4. **(ii) Compare angles $\theta_A$ and $\theta_B$:**
Since $71.57^\circ > 56.31^\circ$, angle B is larger than angle A.
_Conclusion:_ The closer you are to the object, the larger the angle of elevation you observe.
5. **(iii) Find distances from A and B to the object at the top:**
Distances are hypotenuses of right triangles formed by height and horizontal distances.
Distance from A to object:
$$
D_A = \sqrt{h^2 + d_A^2} = \sqrt{6^2 + 4^2} = \sqrt{36 + 16} = \sqrt{52} \approx 7.21 \text{ m}
$$
Distance from B to object:
$$
D_B = \sqrt{h^2 + d_B^2} = \sqrt{6^2 + 2^2} = \sqrt{36 + 4} = \sqrt{40} \approx 6.32 \text{ m}
$$