2 parallel horizontal lines with arrows on both ends to show that they extend indefinitely.

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

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…

2 parallel vertical lines with arrows on both ends to show that they extend indefinitely.

Illustration used to prove the theorem "If three or more parallel lines intercept equal segments on…

3 parallel horizontal lines with arrows on both ends to show that they extend indefinitely.

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…

3 parallel vertical lines with arrows on both ends to show that they extend indefinitely.

4 parallel horizontal lines with arrows on both ends to show that they extend indefinitely.

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…

4 parallel vertical lines with arrows on both ends to show that they extend indefinitely.

5 parallel horizontal lines with arrows on both ends to show that they extend indefinitely.

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…

5 parallel vertical lines with arrows on both ends to show that they extend indefinitely.

6 parallel horizontal lines with arrows on both ends to show that they extend indefinitely.

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…

6 parallel vertical lines with arrows on both ends to show that they extend indefinitely.

Illustration of the construction used to create straight line parallel to a given straight line through…

The cross-ratio of four points in a line is equal to the cross-ratio of their projections on any other…

Parallel lines are drawn by using a triangle in combination with a T-square. To draw a line parallel…

Parallel lines are drawn by holding the triangle against the T-square at an angle, or another triangle,…

Illustration that shows if two parallel lines are cut by three or more transversals that pass through…

Illustration that shows if two parallel lines are cut by three or more transversals that pass through…

Illustration used to prove "The line joining the mid-points of two sides of a triangle is parallel to…

An illustration showing the construction used to erect a parallel line. "With C as a center, draw the…

"Observe: That when drawn above the level of the eye, the bottom faces can be seen. (Boxes H, C and…

Illustration to show that if parallel lines are cut by any number of parallels, the corresponding intercepts…

Illustration to show that if a line is drawn through two sides of a triangle parallel to the third side,…

Illustration to show that if a line divides two sides of a triangle proportionally, it is parallel to…

Illustrations to show that if two parallel lines are cut by a transversal, the bisectors of the interior…

Any system of coordinate axes to another set which is parallel to the former, but with different origins.

Illustration used to prove "The line bisecting one side of a triangle and parallel to another side bisects…

An 8-inch sphere cut by parallel planes, one 2 inches from center and the other 6 inches from center.…

An illustration of a zone of a sphere. A zone occurs when a sphere is cut by parallel planes that are…

An illustration of a zone of a sphere. A zone occurs when a sphere is cut by parallel planes that are…

Illustration used to prove that "If two straight lines are parallel to a third straight line, they are…

Illustration used to prove the theorem, "If two straight lines are cut by a transversal making a pair…

Illustration used to prove the theorem, "If two parallel lines are cut by a transversal, the alternate…

Illustration used to prove the theorem "The line bisecting one of the non parallel sides of a trapezoid…