1. **Problem Statement:** Two points are 40 m apart along a straight path observing a flagpole. The angle of elevation from the first point is 30° and from the second point is 45°. We need to find:
a) The height of the flagpole.
b) The distance from the first point to the flagpole.
2. **Setup and Formula:** Let the distance from the first point to the base of the flagpole be $x$ meters.
The distance from the second point to the flagpole is then $x - 40$ meters (since the points are 40 m apart).
Let the height of the flagpole be $h$ meters.
Using the tangent of the angles (since tangent relates opposite side to adjacent side in a right triangle):
$$\tan(30^\circ) = \frac{h}{x}$$
$$\tan(45^\circ) = \frac{h}{x - 40}$$
3. **Calculate Tangent Values:**
$$\tan(30^\circ) = \frac{1}{\sqrt{3}}$$
$$\tan(45^\circ) = 1$$
4. **Express $h$ from both equations:**
From first point:
$$h = x \times \frac{1}{\sqrt{3}} = \frac{x}{\sqrt{3}}$$
From second point:
$$h = 1 \times (x - 40) = x - 40$$
5. **Set the two expressions for $h$ equal:**
$$\frac{x}{\sqrt{3}} = x - 40$$
6. **Solve for $x$:**
Multiply both sides by $\sqrt{3}$:
$$x = \sqrt{3}(x - 40)$$
$$x = \sqrt{3}x - 40\sqrt{3}$$
Bring terms involving $x$ to one side:
$$x - \sqrt{3}x = -40\sqrt{3}$$
$$x(1 - \sqrt{3}) = -40\sqrt{3}$$
$$x = \frac{-40\sqrt{3}}{1 - \sqrt{3}}$$
Multiply numerator and denominator by the conjugate $(1 + \sqrt{3})$ to rationalize:
$$x = \frac{-40\sqrt{3}(1 + \sqrt{3})}{(1 - \sqrt{3})(1 + \sqrt{3})} = \frac{-40\sqrt{3} - 40 \times 3}{1 - 3} = \frac{-40\sqrt{3} - 120}{-2}$$
$$x = \frac{40\sqrt{3} + 120}{2} = 20\sqrt{3} + 60$$
7. **Calculate numerical value of $x$:**
$$20\sqrt{3} \approx 20 \times 1.732 = 34.64$$
$$x \approx 34.64 + 60 = 94.64 \text{ meters}$$
8. **Calculate height $h$ using $h = x - 40$:**
$$h = 94.64 - 40 = 54.64 \text{ meters}$$
**Final answers:**
- Height of the flagpole $h \approx 54.64$ meters.
- Distance from the first point to the flagpole $x \approx 94.64$ meters.
Flagpole Observation 33C12A
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