I believe there was an expression for it, it was something like 'x and z come into or meet at a similarity when it comes to.......'
A, B and C are similar in that they share some of the same features. A, B and C share the same mathematical features.
There is similarity between A, B and C because [argument].
The arguments used by A, B and C converge when describing [some thing].
A and B have something in common.