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Radical
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The square root sign. |
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Radius
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Half the diameter of a circle, or the distance from any point to the center. |
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Random Number
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A number that is supposedly chosen with no better odds than any other number. It is impossible to generate a true random number, but a computer can come close. |
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Ratio
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The number of one object compared to another. 4:1 is the ratio of arms and legs to bodies on most people. |
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Ray
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A line that has one end-point, but continues infinitely in the other direction. |
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Real Number
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Any number, positive or negative, that is not imaginary. 4/3, 2.5, 0, and -8 are all examples of real numbers. |
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Reciprocal
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The opposite of a numner or fraction. 2/1 is the reciprocal of 1/2. |
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Rectangle
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A quadrilateral that has four 90 degree angles. Squares are a type of rectangle. |
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Regular Polygon
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A polygon that has all of its sides equal and all of its angles congruent. |
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Remainder
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What is left over after a number is divided into another number. For instance, in 12 divided by 5, the remainder is two. |
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Rhombus
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A quadrilateral that has equal sides but oblique angles, like a squashed square. |
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Right Angle
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An angle that measures 90 degrees. It is formed when two lines meet like in a plus sign + |
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Right Triangle
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A triangle that contains one 90 degree angle. |
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Range
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The possible output values of a function, usually the y-values in a simple x-y plot. When you use all of the input (x) values, you will get the entire range as output.
Simple linear functions have a range of all real numbers, but more complicated functions often have restricted sets. Parabolas, for example, will have a range that extends from the vertex of the parabola in one direction. Sine waves have a range from -1 to 1. |
