Let ABC be a triangle, and let X, Y, Z be three points on the segments BC, CA, AB, respectively. Denote by X′, Y′, Z′ the reflections of these points X, Y, Z in the midpoints of the segments BC, CA, AB, respectively. Prove that \left\vert XYZ\right\vert \equal{}\left\vert X^{\prime}Y^{\prime}Z^{\prime}\right\vert. geometrygeometric transformationreflection3D geometryprismgeometry theorems