A(-8;3)
B(4;-5)
[tex]S_{AB} = (\frac{-8+4}{2} ; \frac{3+5}{2} ) = (\frac{-4}{2};\frac{8}{2} ) = (-2;4)[/tex]
prosta AB:
[tex]\left \{ {{3=-8a+b} \atop {-5 = 4a+b}} \right. \\\left \{ {{b=3 + 8a} \atop {-5 = 4a+ 3 + 8a}} \right. \\\left \{ {{b=3 + 8a} \atop {12a = -8}} \right. \\\left \{ {{b=3 +8a} \atop {a = -2/3}} \right. \\\left \{ {{b=-7/3} \atop {a -2/3}} \right.[/tex]
y = (-2/3)x - 7/3
prosta symetralnej:
y₂ = a₂x + b₂
a₂ = -1/a
a₂ = -1/(-2/3)
a₂ = 3/2
y₂ = (3/2)x + b₂ ; S(AB)
4 = (3/2)*(-2) + b₂
4 = -3 + b₂
b₂ = 7
y₂ = (3/2)x + 7
