### Relationships Between 4 Angles

Illustration showing four angles that can be used to define different relationships, such as adjacent,…

### Relationships Between 4 Angles

Illustration showing four angles that can be used to define different relationships, such as adjacent,…

### Relationships Between 6 Angles

Illustration showing six angles that can be used to define different relationships, such as adjacent,…

### Right Angles With Same Vertex

An illustration showing when one straight line meets another straight line and makes the adjacent angles…

### Angles With Same Vertex

An illustration of angles with the same vertex made up of 4 lines.

### Sum of Angles

Illustration showing that the sum of angle 1 and angle 2 is angle ABC.

### Superposition of Angles

Illustration of the superposition of two angles to compare magnitudes of the same kind.

### Supplementary Angles

Illustration of supplementary angles. Two angles whose sum is a straight angle.

### Supplementary Angles

Illustration of supplementary angles. Two angles whose sum is a straight angle. This can be used tow…

### Supplementary Angles

Illustration of supplementary angles. Two angles whose sum is a straight angle. This can be used tow…

### Supplementary Angles

Illustration of supplementary angles. Angles LMK and KMH are supplementary.

### Supplementary Angles

Illustration showing that angles 1 and 2 are supplementary.

### Supplementary and Right Angles

Illustration showing angles 1 and 2 are supplementary and angles ACD and DCB are supplementary. Also,…

### Vertical Angles

Vertical angles are when two angles have the same vertex, and the sides of the one are prolongations…

### Vertical Angles

Illustration showing that angles 1 and 2 are vertical and angles 3 and 4 are vertical.

Anglesite.

### Apatite

"Hexagonal; tri-pyramidal. Crystals usually long prismatic in habit; sometimes short prismatic or tabular.…

### Apatite

"Hexagonal; tri-pyramidal. Crystals usually long prismatic in habit; sometimes short prismatic or tabular.…

Apophyllite.

Apophyllite.

### Apophyllite

"Tetragonal. Usually shows a combination of prism of second order, pyramid of first and basal plane."…

### Aragonite

"Orthorhombic. Acicular pyramidal; consisting of a prism terminated by a combination of a very steep…

### Aragonite

"Orthorhombic. Tabular; consisting of prominent brachypinacoid faces modified by a prism and a low brachydome."…

### Bisecting an Arc

Illustration used to show how to bisect a given arc.

### Arch

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

### Arch

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

### Arch

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

### Arch

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

### Area of Circle with Triangles

"In the triangle above, the line AB is its altitude. Since we know how to find the area of one triangle,…

### Area of Hexagon

Illustration showing how to find the area of a hexagon using the triangles that make it up.

### Area of Sphere

"It is found that the cord covering the curved surface is twice as long as the one covering the flat…

### Area of Sphere

"The bases of the pyramids are considered as forming the surface of the sphere, while the altitude of…

### Arrow Pointing Left

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

### Arrow Pointing Left

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

### Arrow Pointing Left

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

### Arrow Pointing Left

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

### Arsenopyrite

"Orthohombric. Usually in tabular diamond-shaped crystals, formed by a short prism terminated by low…

### Oblique Axes

Angles on a modified coordinate plane.

### Rectangular Axes

Transforming from one set of rectangular axes to another with the same origin, but different direction.

Axinite.

### Axinite

"Triclinic. Crystals usually thin with sharp edges but varied in habit." — Ford, 1912

### Symmetry axis

"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through…

Barite.

### Barite

"Orthohombic. Crystals usually tabular parallel to base; often diamond shaped because of the presence…

### Barite

"Orthohombic. Crystals usually tabular parallel to base; often diamond shaped because of the presence…

### Bear

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

### Bear

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

### Bear

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

### Bear

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

### Bearded Man in a Tophat

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

### Bearded Man in a Tophat

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

### Bearded Man in Tophat

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

### Bearded Man in Tophat

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

### Beryl

"Hexagonal. Strong prismatic habit. Frequently vertically striated and grooved. Forms usually present…

### Beryl

"Hexagonal. Strong prismatic habit. Frequently vertically striated and grooved. Forms usually present…

### Beta Fish

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

### Beta Fish

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

### Beta Fish

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

### Beta Fish

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

### Angle Bisector

Illustration showing that the bisector of a given angle is the locus of points equidistant from the…