出典:Wikipedia
出典:『Wikipedia』 (2011/06/22 18:36 UTC 版)
In classical geometry, a radius of a circle or sphere is any line segment from its center or axis of symmetry to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its circumradius, the radius of its circumscribed circle or circumscribed sphere. In either case, the radius may be more than half the diameter, which is usually defined as the maximum distance between any two points of the figure. The inradius of a geometric figure is usually the radius of the largest circle or sphere contained in it. The inner radius of a ring, tube or other hollow object is the radius of its cavity.
the gamut
the radius of action
直径で
a curve
the side of something
the earth's axis
角度の