Fie ABCDdreptunghiul si O pc de in tresectie al diagonalelor, in triunghiul AOB isoscel deoarece diag se injumatatesc, se duce inaltimea OE. Atunci aplic fc trigonometrice in Δ AOE:
sin O/2=AE/AO, ADICA sin 60= AE/6, AE =6√3/2=3√3, DECI AB= 2*AE=6√3
cos O/2=OE/AO adica cos 60= OE/6, OE= 6/2=3 deci AC= 2*OE=6.
AB reprezinta lungimea cercului deci L=2πR, 6√3=2πR, R=6*1.73/2*3.14=10.38/6.28=1.65
A laterala= 2πRG=2π1.65*6=19.8π
Vol=πR²G=π1.65²6=π2.72*6=16.32π
