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− | 3-D, or 3D, typically refers to something with three spatial dimensions, e.g., a cube. It is the term for an object with length, width, and height.
| + | #REDIRECT [[3D Geometry]] |
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− | 3D Geometry deals with objects in 3 dimensions. For example, a drawing on a piece of paper is 2-dimensional since it has length and width. A baseball, on the other hand, is three-dimensional because it not only has length and width, but also depth.
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− | Contents
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− | 1 Making 3D Problems 2D
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− | 1.1 Example
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− | 1.1.1 Solution
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− | 2 See also
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− | Making 3D Problems 2D
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− | A very common technique for approaching 3D Geometry problems is to make it 2D. We can do this by looking at certain cross-sections of the diagram one at a time.
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− | Example
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− | On a sphere with a radius of 2 units, the points <math>A</math> and <math>B</math> are 2 units away from each other. Compute the distance from the center of the sphere to the line segment <math>AB.</math>
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− | Solution
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− | First, we note that the distance of a point to a line is usually meant to be the shortest distance between the point and the line. This occurs when the perpendicular to the line segment through the point is drawn.
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− | Now that we know what we are looking for, we can choose an appropriate cross-section to look at. We choose to look at the cross-section containing <math>A, B</math> and the center of the sphere as shown in the following diagram:
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− | Sphere3d.PNG
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− | We now draw in the perpendicular to <math>AB</math>:
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− | Sphere3dtriangle.PNG
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− | From here, we can note the 30-60-90 triangle, or the Pythagorean Theorem, to find that <math>x = \sqrt{3}</math> units.
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− | See also
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− | Geometry
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− | Sphere
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− | Cylinder
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− | Cone
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− | Cube
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− | Platonic solids
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− | Tetrahedron
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− | Octahedron
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− | Dodecahedron
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− | Icosahedron
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− | Rhombic dodecahedron
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