### Equal Triangles

Illustration showing two equal triangles.

### Equal Triangles by Side Side Side

Illustration showing two equal triangles. This can be used to show that two triangles are equal if the…

### Equal Right Triangles by Hypotenuse Leg

Illustration showing two equal right triangles. This can be used to show that two right triangles are…

### Similar Triangles

Illustration of two similar triangles, abc and ABC.

### Similar Triangles

Illustration of a triangle divided by a parallel line to form two similar triangles.

### Three Triangles Used to Compare Sides

Illustration showing three triangles. This is used to show the following theorem: If two triangles have…

### Triangular Double Arch

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

### Triangular Double Arch

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

### Triangular Double Arch

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

### Triangular Double Arch

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

### Trisoctahedron

"The trisoctahedron is a form composed of twenty-four isosceles triangular faces, each of which intersects…

### Tristetrahedron

"The faces of the tristetrahedron correspond to one-half the faces of a trapezohedron." — Ford,…

### Construction Of Two Circles That Tangent Themselves and 2 Given Lines

An illustration showing how to construct two circles that tangent themselves and two given lines. "Draw…

### Intersection of Two Cones

"The cone B would be developed by cutting a right section as S—S whose stretchout will be a circle…

### Two Cylinders with Axes Not Intersecting

"If the cylinder A were to be developed a right section as at S—S would have to be taken, whose…

### Intersection of Two Cylinders

"The intersection of two cylinders might represent a dome on a boiler. If the top view of cylinder A…

### Segment, Vertical Line

Illustration of a vertical line segment. A line segment is a section of a line with definite endpoints.

### Segment, Vertical Line

Illustration of a vertical line segment. A line segment is a section of a line with definite endpoints.…

Vesuvianite.

Vesuvianite

### Vesuvianite

"Tetragonal. Prismatic in habit. Often vertically striated. Common forms are prisms of first and second…

### Vesuvianite

"Tetragonal. Prismatic in habit. Often vertically striated. Common forms are prisms of first and second…

### Vulture

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

### Vulture

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

### Vulture

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

### Vulture

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

### Water Skier

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

### Water Skier

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

### Water Skier

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

### Water Skier

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

### Wernerite

"Tetragonal; tripyramidal. Crystals usually prismatic. Prominent forms are prisms of the first and second…

### Wernerite

"Tetragonal; tripyramidal. Crystals usually prismatic. Prominent forms are prisms of the first and second…

### Woman Kneeling

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

### Woman Kneeling

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

### Woman Kneeling

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

### Woman Kneeling.

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

### Woman Standing

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

### Woman Standing

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

### Woman Standing

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

### Woman Standing

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

### Yacht

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

### Yacht

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

### Yacht

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

### Yacht

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

### Zincite

"A crystal of zincite with a prism terminated by a pyramid above a basal pinacoid below." — Ford,…

Zircon.

Zircon.

Zircon.

Zircon.

### Zircon

"Tetragonal. Crystals usually show a simple combination of prism and pyramid of the first order. The…