1. **Problem statement:**
From an aeroplane at a horizontal distance of 1050 m from the base of a control tower, the angles of depression to the top and base of the tower are 36° and 41° respectively. We need to find:
(i) The height of the control tower.
(ii) The shortest distance between the aeroplane and the base of the control tower.
2. **Diagram and variables:**
Let the height of the aeroplane above the ground be $h_a$.
Let the height of the control tower be $h_t$.
The horizontal distance from the aeroplane to the base of the tower is $d = 1050$ m.
3. **Using trigonometry:**
The angle of depression to the top of the tower is 36°, so the angle between the horizontal line from the plane and the line of sight to the top is 36°.
The angle of depression to the base of the tower is 41°.
4. **Formulas:**
From the right triangle formed by the aeroplane, the top of the tower, and the horizontal line:
$$\tan(36^\circ) = \frac{h_a - h_t}{d}$$
From the right triangle formed by the aeroplane, the base of the tower, and the horizontal line:
$$\tan(41^\circ) = \frac{h_a}{d}$$
5. **Calculate $h_a$ from the base angle:**
$$h_a = d \times \tan(41^\circ) = 1050 \times \tan(41^\circ)$$
Calculate $\tan(41^\circ)$:
$$\tan(41^\circ) \approx 0.8693$$
So,
$$h_a = 1050 \times 0.8693 = 912.765$$
6. **Calculate $h_t$ from the top angle:**
$$\tan(36^\circ) = \frac{h_a - h_t}{d} \Rightarrow h_t = h_a - d \times \tan(36^\circ)$$
Calculate $\tan(36^\circ)$:
$$\tan(36^\circ) \approx 0.7265$$
So,
$$h_t = 912.765 - 1050 \times 0.7265 = 912.765 - 762.825 = 149.94$$
7. **Height of the control tower:**
$$\boxed{150 \text{ m (nearest metre)}}$$
8. **Shortest distance between the aeroplane and the base of the tower:**
This is the straight line distance from the aeroplane to the base, which is the hypotenuse of the right triangle with legs $h_a$ and $d$:
$$\text{Distance} = \sqrt{d^2 + h_a^2} = \sqrt{1050^2 + 912.765^2}$$
Calculate:
$$1050^2 = 1,102,500$$
$$912.765^2 \approx 833,191.5$$
Sum:
$$1,102,500 + 833,191.5 = 1,935,691.5$$
Square root:
$$\sqrt{1,935,691.5} \approx 1,391.3$$
9. **Shortest distance:**
$$\boxed{1391 \text{ m (nearest metre)}}$$
Control Tower 3A9E3F
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