Three-dimensional shapes are all around us--from an ice cream cone to a shoebox. The term 3D is short for, "three dimensional," which refers to the space in which we live. Objects that are three-dimensional have height, length and width. Unlike one-dimensional shapes, 3D figures have curved edges and flat surfaces known as faces. The location of the face of a 3D figure depends on the shape, each having its own distinct characteristics. The most common three-dimensional shapes are spheres, cylinders, cones and cubes.
A sphere is a perfectly symmetrical three-dimensional shape that does not have corners. The sphere is the only standard 3D shape that doesn't not have a flat surface. For an object to be classified as a sphere, all of the points of the object must have the same length from the centre. This specific requirement cancels out many shapes that may appear to be spheres but mathematically are not; these shapes are called spheroids. The best example of a spheroid is the plant Earth, which appears as a sphere, but all of the points of the Earth are not the same distance from the centre.
A cube is a standard three-dimensional shape that is also known as a hexahedron. Hexahedron literally mean "six faces." It has 12 edges and eight corner points. Cubes are one of five shapes called platonic solids, which are shapes whose sides are symmetrical and have three faces that meet at one corner. Common cubes are dice, boxes, and some types of crystals. In nature, viruses are the most common cube-structured organism that can take the form of crystals.
A shopping trip at the grocery store will expose a number of 3D geometrical shapes, including a cylinder. Jars of peanut butter, a container of salt or a bottle of cooking spray are all examples of cylinders. Cylinders are shapes that have one curve and a flat base and top, which are the faces of the figure. There are two types of cylinders: circular, which is the most common form, and the elliptical. Elliptical cylinder refers to the elliptical-shaped base and top.
Cones are one of the more simple three-dimensional shapes. A cone usually has a circle flat base that is connected to one curved side. The curved side of the cone is a rotated triangle. Cones look different if the base is more stretched or constricted. Cones usually are classified based on the axis of the figure, which is basically an imaginary line. The most common cone is the right circular cone, which has an axis that passes through the centre of the shape. An oblique cone has an axis that does not pass through the centre; it may appear slanted depending on how far away the axis is from the centre.
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