1. **Problem Statement:**
You want to plot a polygon step-by-step using bearings and distances, converting bearings to coordinates, checking closure, and calculating area.
2. **Formula for Latitude and Departure:**
Given a side length $L$ and bearing angle $\theta$, compute:
$$\text{Latitude } (\Delta Y) = L \times \cos(\theta)$$
$$\text{Departure } (\Delta X) = L \times \sin(\theta)$$
Note: Adjust signs based on quadrant (N/S and E/W).
3. **Example Calculation:**
For side AB = 189.53 m, bearing S 6°15' W ($\theta = 6.25^\circ$):
$$\cos(6.25^\circ) = 0.9941 \Rightarrow \Delta Y = 189.53 \times 0.9941 = 188.41$$
$$\sin(6.25^\circ) = 0.1089 \Rightarrow \Delta X = 189.53 \times 0.1089 = 20.64$$
Since bearing is S-W, both $\Delta Y$ and $\Delta X$ are negative:
$$\Delta Y = -188.41, \quad \Delta X = -20.64$$
4. **Calculate Coordinates:**
Start at Point A $(0,0)$.
Point B:
$$X_b = X_a + \Delta X = 0 - 20.64 = -20.64$$
$$Y_b = Y_a + \Delta Y = 0 - 188.41 = -188.41$$
Repeat for other points by adding their respective $\Delta X$ and $\Delta Y$.
5. **Traverse Closure Check:**
Sum all $\Delta X$ and $\Delta Y$ for all sides:
$$\sum \Delta X \approx 0, \quad \sum \Delta Y \approx 0$$
If sums are close to zero, the polygon is closed correctly.
6. **Calculate Diagonals:**
Use distance formula between points, e.g., for diagonal AC:
$$d = \sqrt{(X_c - X_a)^2 + (Y_c - Y_a)^2}$$
7. **Divide Polygon into Triangles:**
Example triangles: $\triangle ABC$, $\triangle ACD$, $\triangle ADE$.
8. **Compute Area Using Heron's Formula:**
For triangle with sides $a,b,c$:
$$s = \frac{a+b+c}{2}$$
$$A = \sqrt{s(s-a)(s-b)(s-c)}$$
Sum areas of all triangles for total polygon area.
This step-by-step method helps you manually plot polygons from bearings and distances.
If you want, I can also show the shortcut shoelace method next!
Polygon Plotting 4A42E7
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.