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

Lines, 2 Parallel Horizontal

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 line is half the length of the bottom line.

Lines, 2 Parallel Horizontal

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 up when read from left to right.

Lines, 2 Parallel Slanted

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 down when read from left to right.

Lines, 2 Parallel Slanted

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.

Lines, 2 Parallel Vertical

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 one transversal, they intercept equal segments on any other transversal."

4 Parallel Lines Cut By 2 Transversals

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.

Lines, 3 Parallel Horizontal

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 up when read from left to right.

Lines, 3 Parallel Slanted

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 down when read from left to right.

Lines, 3 Parallel Slanted

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.

Lines, 3 Parallel Vertical

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.

Lines, 4 Parallel Horizontal

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 up when read from left to right.

Lines, 4 Parallel Slanted

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 down when read from left to right.

Lines, 4 Parallel Slanted

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.

Lines, 4 Parallel Vertical

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.

Lines, 5 Parallel Horizontal

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 up when read from left to right.

Lines, 5 Parallel Slanted

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 down when read from left to right.

Lines, 5 Parallel Slanted

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.

Lines, 5 Parallel Vertical

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.

Lines, 6 Parallel Horizontal

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 up when read from left to right.

Lines, 6 Parallel Slanted

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 down when read from left to right.

Lines, 6 Parallel Slanted

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.

Lines, 6 Parallel Vertical

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 a given external point.

Construction of a Straight Line Parallel to a Given Straight Line

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 line which lies in the same plane with it.

Cross-Ratio Four Points

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 to the one given, place a triangle against the T-square and move them together until the hypotenuse of the triangle matches the line. Hold the T-square firmly and slide the triangle in the direction of the arrow until the desired position of the parallel line is reached.

Drawing Parallel Lines Exercise

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, then slip the first triangle onto the required position.

Drawing Parallel Lines Using T-square and Triangle

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

Parallel lines

Parallel Lines

Parallel lines

Parallel lines

Parallel Lines

Parallel lines

Parallel lines

Parallel Lines

Parallel lines

Illustration of parallel lines.

Parallel Lines

Illustration of parallel lines.

Illustration that shows if two parallel lines are cut by three or more transversals that pass through the same point, the corresponding segments are proportional.

Parallel Lines Cut by Transversals

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 the same point, the corresponding segments are proportional.

Parallel Lines Cut by Transversals

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 the third side and equal to one half the third side."

Line Joining Midpoints on a Triangle

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 dotted arc ED, with E as a center, draw through C the dotted arc F.C. With the radius FC and E as a center, draw the cross arc at D. Join C with the cross at D, which will be the required parallel line.

Construction Of A Parallel

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 I.) That when drawn below the level of the eye, the top faces can be seen. (Boxes F, B and G.) That when drawn at the left of the eye, the right faces can be seen (Boxes H, D and F)> That when drawn at the right of the eye, the left faces can be seen. (Boxes I, E and G.)" -Foster, 1921

Positioning

"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 are proportional.

Parallel Lines Cut by Parallels, Corresponding Intercepts Proportional

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, it divides those sides proportionally.

Triangle Divided by Parallel Lines to Form Proportionate Triangles

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 the third side.

Triangle Divided by Parallel Lines to Form Proportionate Triangles

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 angles form a rectangle.

Rectangle Formed When Two Parallel Lines are Cut by a Transversal

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

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

Line Bisecting Side of a Triangle

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. This illustration can be used to find the area of the zone and the volume of the segments.

Sphere With 8-inch Diameter Cut by Planes

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 equal distances apart. This illustration is the segment of one base.

Zones or Segments of Spheres

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 equal distances apart. This illustration is the segment of two bases.

Zones or Segments of Spheres

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

A person using a T square to draw straight lines.

T Square

A person using a T square to draw straight lines.

A person using a T square to draw triangles.

T Square

A person using a T square to draw triangles.

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

Parallel Lines Theorem

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 of alternate interior angles equal, the lines are parallel."

Parallel Lines Cut By A Transversal Theorem

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 interior angles are equal."

Parallel Lines Cut By A Transversal Theorem

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 and parallel to the bases bisects the other of the non parallel sides also."

Line Bisecting Trapezoid Sides

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