 ### Segments, 2 Line

2 line segments, AB and CD. AB is half the length of CD. ### Transversal, 2 Lines Intersected By A

2 lines that are intersected by a third line known as a transversal. ### Segments, 2 Parallel Line

2 parallel horizontal line segments. ### Segments, 2 Parallel Line

2 slanted parallel line segments. ### Segments, 2 Parallel Line

2 slanted parallel line segments. ### Intersecting Lines, 2 Perpendicular

2 intersecting lines, one of which is vertical and one of which is horizontal. The intersection forms… ### 4 Parallel Lines Cut By 2 Transversals

Illustration used to prove the theorem "If three or more parallel lines intercept equal segments on… ### Intersecting Lines, 3

3 lines which intersect at a common point. ### Segments, 3 Parallel Line

3 parallel horizontal line segments. ### Segment, 3 Points on a Line

Illustration of line segment AB, which is made up of line segments AC and CB. C is considered the midpoint… ### Intersecting Lines, 4

4 lines which intersect at a common point. ### Intersecting Lines, 4

4 lines which intersect at a common point. ### Segments, 4 Parallel Line

4 parallel horizontal line segments. ### Transversal, 4 Parallel Lines Cut By A

4 parallel lines cut by a 5th line known as the transversal. ### Segments, 5 Parallel Line

5 parallel horizontal line segments. ### Segments, 6 Parallel Line

6 parallel horizontal line segments. ### Segments, 6 Parallel Line

6 slanted parallel line segments. ### Segments, 6 Parallel Line

6 slanted parallel line segments. ### Intersecting Lines, 8

8 lines which intersect at a common point. ### Accidental Point

"That point in which a right line drawn from the eye parallel to another given right line cuts the picture… ### Albite

"Triclinic. Usually in tabular crystals parallel to brachypinacoid." — Ford, 1912 ### Albite

"Triclinic. Sometimes elongated parallel to b crystal axis." — Ford, 1912 ### Albite

"Triclinic. Twinning very common, according to the albite law and evidenced by fine striation lines… ### Amphibole

"Monoclinic. Crystals prismatic in habit; the prism faces make angles of 55 and 125 degrees with each… ### Amphibole

"Monoclinic. Crystals prismatic in habit; the prism faces make angles of 55 and 125 degrees with each… ### Angelfish

Tangrams, invented by the Chinese, are used to develop geometric thinking and spatial sense. Seven figures… ### Angelfish

Tangrams, invented by the Chinese, are used to develop geometric thinking and spatial sense. Seven figures… ### Angelfish

Tangrams, invented by the Chinese, are used to develop geometric thinking and spatial sense. Seven figures… ### Angelfish

Tangrams, invented by the Chinese, are used to develop geometric thinking and spatial sense. Seven figures… ### Angle

Finding the angle between two lines whose equations are in intercept form. ### Acute Angle

An illustration showing an angle the is less than a right angle. This is an acute angle. ### Construction Of A Divided Angle

An illustration showing the construction used to divide an angle into two equal parts. "With C as a… ### Construction Of A Divided Angle

An illustration showing the construction used to divide an angle into two equal parts when the lines… ### Perpendiculars To The Sides Of An Angle

Illustration used to show "The two perpendiculars to the sides of an angle from any point in its bisector… ### Perpendiculars To The Sides Of An Angle

Illustration used to show "The two perpendiculars to the sides of an angle from any point not in its… ### Plane Angle

An illustration of a plane angle with vertex E and sides EF and ED. ### Straight Angle

An illustration showing a straight angle. When the sides of an angle extend in opposite directions,… ### Angles

Showing different types of angles: right, acute, and obtuse. ### 360° Sum of Angles

Illustration showing that the sum of all the angles about a point equals 360°. ### Acute and Reflex Angles

Illustration showing two positive angles; angle 1 being the acute angle and angle 2 being the reflex… ### Acute, Obtuse, Straight, Right, And Reflex Angles

An illustration showing acute, obtuse, straight, right, and reflex angles. An illustration of two angles that are adjacent. They have the same vertex and a common side between… Angles 1 and 2 are adjacent angles. Two angles with a common vertex and a common side between them are… ### Complementary Angles

Illustration of complementary angles. Two angles whose sum is a right angle. ### Complementary Angles

Illustration showing that angles 1 and 2 are complementary. ### Difference of Angles

Illustration showing that the difference between angle 1 and angle 2 is angle ABC. ### Equal Right Angles

Illustration used to prove that all right angles are equal. ### Obtuse And Reflex Angles

An illustration showing an angle the is greater than a right angle and less than a straight angle. This…