Inverse points

Inverse \In*verse"\, a. [L. inversus, p. p. of invertere: cf. F.
   inverse. See {Invert}.]
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   1. Opposite in order, relation, or effect; reversed;
      inverted; reciprocal; -- opposed to {direct}.
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   2. (Bot.) Inverted; having a position or mode of attachment
      the reverse of that which is usual.
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   3. (Math.) Opposite in nature and effect; -- said with
      reference to any two operations, which, when both are
      performed in succession upon any quantity, reproduce that
      quantity; as, multiplication is the inverse operation to
      division. The symbol of an inverse operation is the symbol
      of the direct operation with -1 as an index. Thus sin-1 x
      means the arc or angle whose sine is x.
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   {Inverse figures} (Geom.), two figures, such that each point
      of either figure is inverse to a corresponding point in
      the order figure.

   {Inverse points} (Geom.), two points lying on a line drawn
      from the center of a fixed circle or sphere, and so
      related that the product of their distances from the
      center of the circle or sphere is equal to the square of
      the radius.

   {Inverse ratio}, or {Reciprocal ratio} (Math.), the ratio of
      the reciprocals of two quantities.

   {Inverse proportion}, or {Reciprocal proportion}, an equality
      between a direct ratio and a reciprocal ratio; thus, 4 : 2
      : : 1/3 : 1/6, or 4 : 2 : : 3 : 6, inversely.
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