Question

In a triangle ABC ;
D,E,F are an midpoint 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
2 1

now we use section formula,
for x co-ordinate
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2={2( -7 )+x}/3

6=-14 + x
x=20

y co-ordinate of A
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-1={4 (2)+y}/3

-3=8+y

y=-11
so,
co-ordinate of A =(20,-11)