I know this is pretty old, but I'm on the same problem and I'm stuck as well.
You say there's infinite planes that intersect with that line, but what exactly is the question asking for then?
It says "Find all planes in R^3", if there's infinite planes then what am I writing?
This is...
Homework Statement
An upward and downward pulse, otherwise identical in shape are propagating in opposite directions along a stretched string. At the instant they overlap completely, the displacement of the string is exactly zero everywhere. How does this situation differ from true...