a) Patrulaterul BPCS = paralelogram (diagonalele se injumatatesc)⇒SC || BP
patrulaterul ARBP = paralelogram ( " " " " " " " " "" " " " "" " " "") ⇒ AR || BP ⇒ AR || SC
SB || PC (in BSCP) PC || AT (in APCT) ⇒ SB || AT
c) BR || AP (in ARBP) AP || TC (in APCT) ⇒ BR || CT