a) Ltoarta=2piR/2=10pi ≈ 10*3,14=31,4 cm
b) V=pi*h(R^2 +r^2 + Rr)/3 ≈42*3(100+64+80)/3 = 42*244 = 10 248 cm^3
V≈10 248 cm^3 = 10,248 dm^3
c) Alat = piG(R+r)
G=rad(h^2 +(R-r)^2) = rad(1764+4)= rad1768 = rad(2^3 * 13 *17) = 2rad(26*17) = 2rad(442) ≈ 2*21,023≈ 2*21 = 42 cm^2
Alat ≈ pi*42*18 ≈ 3*756 = 2268 cm^2
Alat ≈ 2268cm^2