ℓell is the perpendicular bisector of segment \overline{km} km start overline, k, m, end overline. Nnn is any point on \ellℓell. Line l intersected at its midpoint labeled l at a right degree angle by line segment m k. There is a point n on line l that is on the start of it. Dashed lines slant from point m to point n and from point k to point n. Line l intersected at its midpoint labeled l at a right degree angle by line segment m k. There is a point n on line l that is on the start of it. Dashed lines slant from point m to point n and from point k to point n. What theorem can we prove by reflecting the plane over \ellℓell?