How to find the geographic cordinates of a point in a segment?

i have two geographic cordinates of two points forming a segment. i need to know cordinates (longitude and latitude) of a specific point of the segment for example the point in the middle or a point separated by a given distance from one of the two ends points of the segment?

Can any one give me an idea please

Thanks for your help

[Image Analyst]

Is this using the Mapping Toolbox or the Image Processing Toolbox?