jawaban+caranya ya.. plisss

AC^2=AB^2+BC^2-2*AB*BC cos 120
(p√7)^2=p^2+BC^2-2*p*BC*(-1/2)
BC^2+pBC+p^2-7p^2=0
BC^2+pBC-6p^2=0
(BC+3p)(BC-2p)=0
BC=-3p atau BC=2p

A ke C melaui B =AB+BC=p+2p=3p