Question

In a triangle ABC , D,E and F are mid points of BC, CA and AB respectively.If D(-7,4) F(3,-5) and centriod of ΔDEF is (2,-1) then find the coordinates of A.

Answer 1

A===========G===========D
where G is centroid of traingle
we know ,
AG:GD=2:1
use section formula ,
let (r,s) is the point of A
2={2(-7)+r}/(2+1)
6=-14+r
r=20
same way,
-1={2(4)+s}/3
-3=8+s
s=-11

hence point A= (20,-11)