Googled and tried to look on Esri's forum but couldn't get anything. Rather got things which were verifying if the point is within a polygon or not. But I want to know, if I have starting point and end point of a line on a map with datum as WGS84 and geographic coordinate system, and I have another point in the same system, how can I verify if the point lies on the line or not? I am pretty new in the field of GIS, so maybe it's a very trivial question.
Here are a few links to get you started in the right direction. This is not simple Euclidean geometry question.
See Charles F. F. Kinney's (cffk's) response to Finding projection of point to line?
The C code Charles mentions is at this link to his intersect.ccp file
His very detailed article entitled Algorithms for geodesics deals with math behind the problems of intersection and interception in Section 8 Ellipsoidal gnomonic projection.
Here is a more general discussion presented in simpler terms at Ask Dr. Math
A geoprocessing approach would simply involve using the Intersect tool on the two layers and outputting a point feature class where the points that fell on the lines would merge the point and line attributes and the points that did not fall on the lines would not be in the output.