An expression for galactic density has been derived from galactic rotation curves using Burbidge technique, in which rotational velocity v(r) is related to the galactic density at a given distance r. Abel's integral has been used to evaluate the galactic density ρ (r, k) . The derived density law has been applied to spiral galaxies with a general observed rotation curves with a turn-over at some distance r t , so we got two different density forms ρ 1 (r, k) and ρ 2 (r, k) for the core and for disk and halo of the galaxy respectively.

The density and mass of Spiral galaxy NGC 3672 has been studied as a function of the distance from the center of the galaxy. The mass of the three regions of the galaxy (nucleus, disk and halo) have been calculated and compared with other work. The total mass of NGC 3672 is found to be 1.22×10 11 M o at a radius of 23.7 kpc.