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An undefined term thought of as a location with no size or dimension. It is the most basic building block of geometry. In a two-dimensional coordinate system, its location is represented by an ordered pair of numbers (x, y).
An undefined term thought of as a straight, continuous arrangement of infinitely many points extending forever in two directions. It has length, but no width or thickness, so it is one-dimensional.
An undefined term thought of as a flat surface that extends infinitely along its edges. It has length and width but no thickness, so it is two-dimensional.
The midpoint between (x1,y1) and (x2,y2) is found by using ( (x1+x2)/2 , (y1+y2)/2 )
measure of an angle
The smallest amount of rotation about the vertex from one ray to the other, measured in degrees.
A ray that has its endpoint at the vertex of the angle and that divides the angle into two congruent angles.
A closed figure in a plane, formed by connecting line segments endpoint to endpoint with each segment intersecting exactly two others.
consecutive (angles, sides or vertices of a polygon)
Two angles that share a common side, two sides that share a common vertex, or two vertices that are the endpoints of one side.
The length of the boundary of a two-dimensional figure. For a polygon it is the sum of the lengths of its sides.
A triangle with at least two congruent sides. Note : Most have only two congruent sides, although an equilateral triangle can be considered one as well.
A line segment from the center of a circle or sphere to a point on the circle or sphere. Also, the length of that line segment.
A line that lies in the plane of a circle and that intersects the circle at exactly one point.
An arc of a circle whose endpoints are the endpoints of a diameter. An arc whose degree measure is 180°.
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