Abstract
In this paper, non-lightlike ruled surfaces of constant slope in Minkowski 3-space with a non-lightlike base curve c(s)=∫αt+βn+γbds, where t, n, b are tangent, principal normal and binormal vectors of an arbitrary timelike curve Γ(s) are investigated. Non-lightlike ruled surfaces of constant slope parallel to a tangent of a timelike general helix and normal of timelike slant helix are studied. It is shown that all non-lightlike ruled surfaces of constant slope are developable but not minimal surfaces.