# Geometry Terms

• Construction – a drawing using only two tools a compass and a straight edge
• Segment – a part of a line that has two endpoints
• Bisect – to divide into 2 equal parts
• Midpoint – a point that divides a segment into two equal, or congruent, parts
• Congruent – same measure or length
• Segment Bisector – a line, segment, or ray that goes through the midpoint of a segment
• Radius – the distance from the center to the side of a circle
• Ray – A ray begins at a point and goes on forever in one direction
• Angle – Region between two rays or the amount of rotation about a fixed point
• Vertex – the common endpoint of the two rays that serve as the sides of an angle.
• Perpendicular Lines – two lines that intersect to form a right angle.
• Perpendicular Bisector – A perpendicular line or segment that passes through the midpoint of a segment.
• Point – a location in space
• Parallel Lines – Two lines are parallel if they lie in the same plane and they do not intersect.
• Coordinate Plane – A two-dimensional region determined by a pair of axes and that uses numerical values to represent the location of an object.
• X-Axis – The horizontal number line on the Cartesian coordinate plane.
• Y-Axis – The vertical number line on the Cartesian coordinate plane.
• Origin – the point of intersection of the vertical and horizontal axes of a coordinate plane
• Quadrant – One of the four regions on a Coordinate plane formed by the intersection of the x-axis and the y-axis.
• Ordered Pair – A pair of numbers, (x, y), that indicate the position of a point on a Cartesian plane.
• Coordinate – An ordered pair, (x,y), that locates a point in the plane.
• Transformation   – The mapping, or movement, of all the points of a figure in a plane according to a common operation.
• Translation – a transformation that “slides” each point of a figure the same distance in the same direction.
• Rotation – A transformation that turns a figure about a fixed point at a given angle and a given direction.
• Reflection – A transformation that “flips” a figure over a mirror or reflection line.
• Dilation –  A transformation that changes the size of an object, but not the shape.
• Pre-Image – the original figure before any transformations have taken place
• Image – The result of a transformation.
• Cross Section – the intersection of a three-dimensional figure with a plane
• Ratio – A comparison of two quantities that have the same unit of measure.
• Similar Figures – Figures that have the same shape but not necessarily the same size.
• Congruent Figures – Figures that have the same shape and are the same size.
• Scale Factor – The ratio of corresponding lengths of the sides of two similar figures.

You don’t need to draw the ones below.

• Angle – two segments that share a common endpoint.
• Freehand – without the aid of any tool.
• Parallelogram – Four sides, opposite sides equal, non-right angles
• Proportion – Two or more equal ratios.
• Ratio – Compare two numbers using division
• Rectangle – Four sides, right angles, opposite sides equal
• Rhombus – Four equal sides, non-right angles
• Segment – portion of a line that begins and ends.
• Square – Four sided figure, right angles, equal sides
• Triangle – Three sided figure
• Vertex – point of angle where the 2 segments meet

From Georgia Virtual Learning

http://cms.gavirtualschool.org/Shared/Math/MSMath7