techInterview Discussion

In the xy coordinate plane the line y=mx, with 0<m, is given.  Also given is the point P(a,b) with 0<a, 0<b<ma.  Find points R(r,0) and E(e,me) such that the total distance PR+RE+EP is minimum.

let a point superpositioned with p.
Another point on the penpendicular to x axis

I don't know what you are saying, Yaxiong Zhao.  What are you trying to say?  How is your comment an answer to my question?  I am lost!

Let P' be the symmetry point of P about the x axis, and P'' be the symmetry point of P' of the line y=mx. Then for any points E and R, PE+ER+RP=PE+ER+RP'>=PE+EP'=PE+EP''>=PP''. The E and R that will make those "=" true satisfy the following: E is the intersection point of PP'' and y=mx; R is the intersection point of P'E and the x axis.

Beautifully done, Ruohao Li! Nice! Thanks.