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Angle
The union of two rays with a common vertex.
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Coordinate Plane
Any plane with two perpendicular intersecting
lines. The point of intersection of the lines is called the origin and the
location of any point in the plane can be measured along the two lines, or
axes.
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Degree
A unit of measure for angles. 360 degrees equals one revolution and
2Π radians.
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Initial Side
The side of an angle from which the rotation begins; the initial
position of the ray whose rotation creates the angle.
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Magnitude
The length of a vector
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Minute
A subdivision of a degree. One minute is equal to 
degrees.
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Ordered Pair
The $x$-coordinate and $y$-coordinate, placed together between parentheses
and separated by a comma. An ordered pair specifies a location in the
coordinate plane.
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Origin
The intersection of the $x$-axis and $y$-axis in a coordinate plane.
The location of the origin is (0,0).
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Plot
To draw a point in the coordinate plane at a specific location. Points are
plotted in the coordinate plane.
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Quadrant
One of the four regions in the coordinate plane created by the intersection
of the axes
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Quadrantal Angle
An angle in standard position whose terminal side lies along one of
the axes
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Radian
A unit of measure for angles. 2Π radians equals one revolution and
360 degrees.
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Ray
A part of a line with a fixed endpoint on one end that extends without bound in
the other direction.
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Revolution
A rotation of the magnitude such that the initial side of an angle
coincides with the terminal side; one complete rotation. One revolution
equals 360 degrees and 2Π radians.
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Second
A subdivision of a degree. One second is equal to 
degrees,
or minutes.
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Side
One of the rays that makes up an angle (is a side of the angle).
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Standard Position
The location of an angle such that its vertex lies at the origin and
its initial side lies along the positive $x$-axis.
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Terminal Side
The side of an angle after rotation; the final position of the ray
whose rotation created an angle.
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Vector
A line segment with a starting point and an endpoint that represents motion in
the direction of the endpoint, and which lies in a specific position such that
its direction is fixed.
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Vertex
The common endpoint of two rays that form an angle
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x-axis
One of the two perpendicular lines that form the coordinate plane; usually
the x-axis lies in a horizontal position.
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x-component
The magnitude of a vector in the x direction.
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x-coordinate
The distance between a point and the y-axis.
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y-axis
One of the two perpendicular lines that form the coordinate plane; usually
the y-axis lies in a vertical position.
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y-component
The magnitude of a vector in the y direction.
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y-coordinate
The distance between a point and the x-axis.
