Analyzing the Setup
Imagine a triangular park ΔABC situated on a horizontal plane. A vertical pole of height h stands at a point O on the ground, with its top at point P.
Since the pole is vertical, it is perpendicular to the ground. This implies that the line segment OP is perpendicular to any line in the plane passing through O.
Consequently, we form three right-angled triangles: ΔPOA, ΔPOB, and ΔPOC. In each of these triangles, the angle at O is 90∘, and the height OP is common to all.
The Trigonometric Bridge
The problem states that the angle of elevation from each corner (A, B, and C) to the top of the pole P is identical. Let this constant angle be denoted by α.
In the right-angled triangle ΔPOA, we apply the definition of the tangent function:
Rearranging this expression to solve for the distance from the foot of the pole to the vertex A, we obtain:
Since the height OP and the angle α are identical for all three vertices, the same logic applies to triangles ΔPOB and ΔPOC. Therefore, we find:
The Geometric Revelation
We have arrived at the conclusion that the foot of the pole O is equidistant from all three vertices of the triangular park.
In Euclidean geometry, the unique point that is equidistant from all three vertices of a triangle is defined as the circumcentre of the triangle.
Conclusion: The foot of the pole O must be the circumcentre of ΔABC.
This result is a powerful tool in coordinate geometry and 3D visualization. Whenever a point in space subtends the same angle of elevation to all vertices of a polygon, the projection of that point onto the plane is the circumcentre of the polygon.