A triangle has corners at (7, 2 )(7,2), ( 9, -7), and ,and(1, 4 )#. If the triangle is reflected across the x-axis, what will its new centroid be?

1 Answer
Apr 19, 2016

Coordinates of new centroid are (17/3,1/3)(173,13)

Explanation:

Reflection of a point (x,y)(x,y) in xx-axis is (x,-y)(x,y).

Hence reflection of a triangle having corners at (7,2)(7,2), (9,-7)(9,7) and (1,4)(1,4) will be a triangle with corners at (7,-2)(7,2), (9,7)(9,7) and (1,-4)(1,4).

As coordinates of centroid of a triangle with points at (x_1,y_1)(x1,y1), (x_2,y_2)(x2,y2) and (x_3,y_3)(x3,y3) is ((x_1+x_2+x_3)/3,(y_1+y_2+y_3)/3)(x1+x2+x33,y1+y2+y33) and hence

coordinates of new centroid are ((7+9+1)/3,(-2+7-4)/3)(7+9+13,2+743) or (17/3,1/3)(173,13)