A triangle has corners at (0, 5 ), ( 1, -6), and (8, -4 )#. If the triangle is reflected across the x-axis, what will its new centroid be?

1 Answer
May 18, 2016

(3,5/3)

Explanation:

The centroid C also known as barycenter, of a triangle with vertex given as {a,b,c} is calculated as:
C = (a+b+c)/3. Our triangle has a = (0,5), b= (1,-6), c = (8,-4) so
we have C = (3,-5/3). Reflecting the triangle across the x axis
implies in reflecting also the barycenter. Choosing the x axis facilitate calculations because the C point perpendicular projection over the x axis is exactly its x component with y = 0. Call this projected point C_x = (3,0). The reflected point is calculated as C_r =C + 2 (C_x-C) = (3,5/3)