| The common perpendicular bisectors of parallel sides bisect the angles of the triangle formed by the extensions of the three equal diagonals. |
| How many diagonals are needed to divide a heptagon, a nonagon, and an undecagon into triangles? |
| They can be disturbing unless supported by verticals or opposing diagonals. |
| It may take him many weeks to realize that bishops move only along diagonals and rooks move only along orthorgonals. |
| The composition is effective through the use of converging diagonals and the play of light on the transparent materials. |
| He showed that in any hexagon formed of six tangents to a conic, the three diagonals meet at a point. |
