The component of the radial velocity observed through line broadening depends on the inclination of the star's pole to the line of sight. The derived value is given as formula_1, where "ve" is the rotational velocity at the equator and "i" is the inclination. However, "i" is not always known, so the result gives a minimum value for the star's rotational velocity. That is, if "i" is not a right angle, then the actual velocity is greater than formula_1. This is sometimes referred to as the projected rotational velocity. In fast rotating stars polarimetry offers a method of recovering the actual velocity rather than just the rotational velocity; this technique has so far been applied only to Regulus.