Problem
GEO-B2-M05-P006 Checking Inverse Points
#6
★★☆☆☆ Level 2 of 5
Points \(A\) and \(B\) lie on one ray from \(O\), \(OA=7\), \(OB=28\). Under which inversion with centre \(O\) do they map to each other?
Find \(R\) from \(R^2=OA\cdot OB\).
We have \(R^2=7\cdot 28=196\), hence \(R=14\). The inversion with centre \(O\) and radius \(14\) maps these points to each other.
Another short problem on choosing the radius.