Given points A (100m), B (200m), and C (400m), determine the strike line and dip line of a coal seam using these points.

Point A is at $100\,\text{m}$.
Point B is at $200\,\text{m}$.
Point C is at $400\,\text{m}$.

Since A is $100\,\text{m}$ and C is $400\,\text{m}$, the $200\,\text{m}$ point (let's call it $P_{200}$) on the line segment AC is located one-third of the way from A to C. This is because the elevation difference from A to $P_{200}$ is $200\,\text{m} - 100\,\text{m} = 100\,\text{m}$, and the total elevation difference from A to