1. **Problem statement:** We are given three points A, B, and C with C due west of B, the bearing of A from B is 241°, and AC = CB. We need to find the bearing of A from C.
2. **Understanding bearings:** Bearing is measured clockwise from north. A bearing of 241° from B to A means starting at north at B and rotating 241° clockwise to point towards A.
3. **Set up coordinate system:** Place B at the origin $(0,0)$.
Since C is due west of B, let $C = (-d,0)$ for some positive $d$.
4. **Find coordinates of A relative to B:**
Bearing from B to A is 241°, which is $241° - 180° = 61°$ west of south.
Convert bearing to vector direction:
$$x_A = r \sin(241°) = r \sin(241°)$$
$$y_A = r \cos(241°) = r \cos(241°)$$
Using approximate values:
$$\sin(241°) = \sin(180° + 61°) = -\sin(61°) \approx -0.8746$$
$$\cos(241°) = \cos(180° + 61°) = -\cos(61°) \approx -0.4848$$
So,
$$A = (r \times -0.8746, r \times -0.4848)$$
5. **Use AC = CB:**
Distance $CB = d$ (since $C=(-d,0)$ and $B=(0,0)$).
Distance $AC = |A - C| = \sqrt{(r(-0.8746) + d)^2 + (r(-0.4848) - 0)^2} = d$
Square both sides:
$$(r(-0.8746) + d)^2 + (r(-0.4848))^2 = d^2$$
Expand:
$$r^2 (0.8746^2 + 0.4848^2) + 2 r d (-0.8746) + d^2 = d^2$$
Simplify:
$$r^2 (0.7649 + 0.2350) - 1.7492 r d + d^2 = d^2$$
$$r^2 (1.0) - 1.7492 r d + d^2 = d^2$$
Subtract $d^2$ from both sides:
$$r^2 - 1.7492 r d = 0$$
Factor:
$$r (r - 1.7492 d) = 0$$
Since $r \neq 0$, we have:
$$r = 1.7492 d$$
6. **Find coordinates of A:**
$$A = (1.7492 d \times -0.8746, 1.7492 d \times -0.4848) = (-1.529 d, -0.848 d)$$
7. **Find bearing of A from C:**
Vector from C to A is:
$$\overrightarrow{CA} = A - C = (-1.529 d + d, -0.848 d - 0) = (-0.529 d, -0.848 d)$$
Calculate angle $\theta$ from north (positive y-axis) clockwise to vector $\overrightarrow{CA}$:
First find angle $\alpha$ between vector and positive x-axis:
$$\alpha = \arctan\left( \frac{y}{x} \right) = \arctan\left( \frac{-0.848 d}{-0.529 d} \right) = \arctan(1.603) \approx 58.0°$$
Since both $x$ and $y$ are negative, vector is in third quadrant, so angle from positive x-axis is:
$$180° + 58° = 238°$$
Bearing is measured clockwise from north (positive y-axis). The angle between positive y-axis and vector is:
$$\text{bearing} = 180° + 58° - 90° = 148°$$
Alternatively, bearing from north clockwise is:
$$\theta = 360° - (238° - 90°) = 360° - 148° = 212°$$
Check carefully: Vector angle from positive x-axis is 238°, so from positive y-axis (north) clockwise is:
$$\text{bearing} = (360° + 90° - 238°) \mod 360° = 212°$$
8. **Final answer:**
The bearing of A from C is **212°**.
Bearing From C
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