Math 2.0

Geometry Definition

Centroid

Builds on Affine combination

Definition

Let kk be a positive integer, and let KK be a field in which k≠0k \neq 0. Let AA be an affine space over a KK-vector space, and let p1,…,pkp_1, \dots, p_k be points of AA. The centroid of p1,…,pkp_1, \dots, p_k is the affine combination with all weights equal to 1k\frac{1}{k}: G=1kp1+1kp2+⋯+1kpk.G = \frac{1}{k} p_1 + \frac{1}{k} p_2 + \dots + \frac{1}{k} p_k. The centroid of a triangle ABCABC is the centroid G=13(A+B+C)G = \frac{1}{3}(A + B + C) of its vertices.

Remarks

In ℝn\mathbb{R}^n, the coordinates of the centroid are the means of the coordinates of the points. In ℝn\mathbb{R}^n, the centroid is the point xx that makes the sum ∑i∥x−pi∥2\sum_i \|x - p_i\|^2 smallest. The centroid of two points is their midpoint. The centroid of a triangle is also the centre of mass of a uniform triangular plate.

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Further reading

  1. Web https://en.wikipedia.org/wiki/Centroid, Of a finite set of points
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