If a vertex of a triangle is (1,1) and the mid points of two sides through this vertex are (– 1, 2) and (3,2), then centroid of the triangle is

Let (x1, y1) and (x2, y2) be the other two vertices of the triangle, then x1+12=−1,   y1+12=2⇒x1,y1=(−3,3); similarly x2,y2=(5,3)centroid of the triangle is 1−3+53,1+3+33=(1,7/3)