Răspuns :
A----B------------------C-------------------D
BC=AC-AB=28-7=21
AD=2 ×28=56
CD=AD-AC=56-28=28
BD=BC+CD=21+28
BD=49
Succes!!;D
BC=AC-AB=28-7=21
AD=2 ×28=56
CD=AD-AC=56-28=28
BD=BC+CD=21+28
BD=49
Succes!!;D
AD=2AC
AD=2*28
AD=56
AC=AB+BC
28=7+BC
BC=28-7
BC=21
AC+CD=AD
28+CD=56
CD=56-28
CD=28
BD=BC+CD
BD=21+28
BD=49