G [ ( x₁ +x₂ +x₃ ) / 3 ; ( y₁+y₂+y₃) /3 ] = [ ( 4-2+3) /3 ; ( 2+2-2) /3 ]
G( 5/3 , 1/3)
AB = ( -2-4 ) ·i + ( 1-2 ) ·j = -6·i -j
AC = ( 3-4) ·i + ( -2 -2 ) ·j = -i - 4·j
AG = ( 5/3 - 4 ) ·i + ( 1/3 - 2 ) ·j= - 7/3 · i - 5/3 ·j
fie D ( a, b)
5 ·[ ( a-4)· i + ( b-2)·j ] = ( -12 ·i - 2· j ) - ( -3· i -12 ·j )
5·( a-4) ·i + 5 ·( b-2 )·j = - 9· i + 10 ·j
egalam 5·( a -4) = -9 a = 11/5
b-2 = 2 b=4
