folosesti formula> [tex] \frac{x- x_{A} }{ x_{B} - x_{A} } } = \frac{y- y_{A} }{y_{B} - y_{A} } } [/tex]
AB> [tex] \frac{x-3}{5-3} = \frac{y-5}{4-5} \\ AB: -x+3=2y-10 \\ AB: x+2y-13=0[/tex]
daca M este centru rezulta M este mijlocul diagonalei Rezulta ca [tex] x_{M}= \frac{ x_{D}+ x_{B}}{ 2 } \\ 7=\frac{ x_{D}+ 5}{ 2 } \\ x_{D}=14-5=9 \\ y_{M}= \frac{ y_{D}+ y_{B}}{ 2 } \\ 8=\frac{ y_{D}+ 4}{ 2 } \\ y_{D}=16-4=12[/tex]
Deci are coordonatele D(9,12)
se calculeaza dupa formula celelalte laturi
