how to project vertex along a tangent

*To*: mathgroup at smc.vnet.net*Subject*: [mg123149] how to project vertex along a tangent*From*: Robert Sladen <biz_enquiries at compressionplus3d.co.uk>*Date*: Thu, 24 Nov 2011 06:59:38 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

Hi, I want to project a vertex along its tangent and figure that the vertex normal would be the tangent I would like to use to project the vertex along it so that I can increase or decrease the vertices distance from the origin. The assumption is that the vertex I want to project is not set at the origin. For, instance, if I were to select any vertex on a sphere, how could I then project the vertex along its tangent. Thanks for any help. Rob.