If two vertices of a triangle are (3,7) and (−1,5) and its centroid is (1,3). Find the coordinates of the third vertex.
Centroid of a triangle with vertices (x1,y1);(x2,y2) and (x3,y3) is calculated by the formula
(x1+x2+x33,y1+y2+y33)
Let the third vertex of the triangle be (x,y)
So, centroid =(3−1+x3,7+5+y3)=(1,3)
⇒(2+x3,12+y3)=(1,3)
⇒2+x=3;12+y=9
⇒x=1;y=−3
Hence the third vertex of the triangle is (1,−3)