2 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

2 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

3 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

3 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

4 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

4 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

5 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

5 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

6 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

6 parallel lines with arrows on both ends to show that they extend indefinitely. The lines are slanting…

Illustration of a regular hexagon inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a square, with diagonals drawn, circumscribed about a circle. This can also be described…

Illustration of a square, with 1 diagonals drawn, circumscribed about a circle. This can also be described…

Illustration of a square circumscribed about a circle. This can also be described as a circle inscribed…

Illustration of a square inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a square, with diagonals drawn, inscribed in a circle. This can also be described as…

Illustration showing a circle with an inscribed and circumscribed quadrilateral.

Any four-point on a curve of the second order and the four-side formed by the tangents at these points…

Illustration of a parallelogram with diagonals AC and BD intersecting at point O.

Illustration of a parallelogram with altitude and diagonal drawn.

Illustration of a parallelogram with diagonals drawn to show they bisect each other.

Illustration to show that when lines from two opposite vertices of a parallelogram to the midpoints…

Illustration of a polygon with a diagonal drawn. A diagonal of a polygon is a line joining the vertices…

Quadrilateral with intersecting diagonals and segment connecting midpoints.

Illustration to show that if the diagonals of a quadrilateral bisect each other, the figure is a parallelogram.

Illustration to show that if the diagonals of a parallelogram are equal, the figure is a rectangle.

A heraldic shield with a purple surface, shown by the diagonal lines stretching from the top-right corner…

A heraldic shield with a green surface, represented by the diagonal lines drawn from the top left corner…

A line with arrows on both ends to show that it extends indefinitely. The line is slanting up when read…

A line with arrows on both ends to show that it extends indefinitely. The line is slanting down when…

A line with arrows on both ends to show that it extends indefinitely. The line is slanting up when read…

A line with arrows on both ends to show that it extends indefinitely. The line is slanting down when…

Illustrations of a square with diagonal DB, BE cut off equal to BC, and EF drawn perpendicular to BD…

Illustration of a trapezium, a quadrilateral having no two sides parallel. The diagonal is labeled in…

Illustrations of a trapezoid with a line joining the midpoints of the diagonals.