Question: Given three points of a triangular coral reef at $A(1, 1, 0)$, $B(3, -1, 0)$, and $C(2, 2, 0)$, find the coordinates of the fourth vertex $D$ such that the quadrilateral $ABCD$ is a parallelogram with integer coordinates.

Why are experts and enthusiasts exploring this geometric challenge right now? In part, this question taps into a growing curiosity about spatial relationships—especially as 3D modeling, reef preservation data visualization, and mapping technologies gain traction in science and education. US-based users interested in marine ecosystems, environmental data, or spatial reasoning are increasingly drawn to such precise coordinate puzzles. While the question may appear abstract, it forms a foundational concept used in geographic, architectural, and ecological modeling—where understanding how shapes define space matters deeply.


Understanding the Context

Why This Question Is Gaining attention Across the US
Across digital spaces, users are seeking clear, accurate, and meaningful ways to interpret spatial data—especially when contextualized within real-world environments like coral reef systems. This query isn’t just academic; it supports understanding how physical features connect, backtrack, and extend—valuable in conservation planning, immersive education, and geospatial technology. As mobile-first platforms prioritize intuitive, accurate, and relevant content, questions like this resonate with audiences looking for structured knowledge grounded in geometry and real-world relevance.


How to Find the Fourth Point of a Parallelogram
When three points define one corner of a parallelogram, the fourth vertex can be determined using vector geometry—no complex technology required. For parallelogram $ABCD$, vector $ \vec{AB} $ must equal vector $ \vec{DC} $. This means point $D$ lies such that:

$ D = A + \vec{BC} $
or equivalently,
$ D = C + \vec{AB} $
or
$ D = B + \vec{AC} $

Key Insights

Compute $ \vec{AB} = B - A = (3-1, -1-1, 0) = (2, -2, 0) $
Then $ D = C + \vec{AB} = (2 + 2, 2 - 2, 0 + 0) = (4, 0, 0) $.

Check via vector $ \vec{AD} = (4-1, 0-1, 0) = (3, -1,