Geometry Vocabulary - Carroll County Public Schools

1 Geometry Vocabulary acute angle-an angle circle-the set of all coordinate plane-the diameter-the distance measuring less than points in a plane that grid system in which across the widest part 90 degrees are a given distance the x-axis and y-axis of a circle; twice the from a given point provide reference radius; also defined as points a chord that passes through the center of a circle angle-the turn or bend cube-a three- between two dimensional object intersecting lines, line circumference-the with 6 square faces segments, rays , or distance around the planes edge of a circle. dilation- shrinking or closed figure-the stretching the figure boundary of a simple two-dimensional angle bisector-an region, including angle bisector is a ray shapes with straight cylinder- three- that cuts an angle and curved sides dimensional figure exactly in half, with a curved surface making two equal and two circular bases angles edge- a line segment at the intersection of 45 cone- three- two faces of a dimensional figure polyhedron 45 with a curved surface, a circular base and one apex (point) degree-a unit of attribute- a measure of angles.

2 Characteristic of an there are 360 degrees object, such as color, in a circle equiangular shape, or size triangle- a triangle which all angles are base-a face or surface diagonal- for a congruent (3-D object) or a side congruent- geometric polygon in the plane, (2-D objects) figures having the any line segment considered as the same size and shape; joining non-adjacent bottom part, or all corresponding vertices. foundation of a parts of congruent geometric figure; used figures have the same equilateral triangle- for the purpose of measure a triangle which all measurement the sides are congruent. base face- a polygonal line -one of the three octagon- a polygon plane-one of the three region of a three- undefined figures in with eight sides undefined figures in dimensional figure Geometry , a line has Geometry , a plane is a no thickness, is flat expanse, like a perfectly straight, and sheet of paper, that goes on forever in goes on forever both directions; two points determine a one-dimensional- a heptagon- a polygon unique line figure that has length plane figure-any two with seven sides but no width or dimensional figure height.

3 Point-one of the three line of symmetry-a undefined figures in line over which a parallel lines- Lines Geometry , a point is a hexagon- A polygon figure can be that lie in the same location with no with six sides reflected, resulting in plane and never meet. length, width, and a figure that looks Also, planes lying in height. exactly like the space that never meet. original polygon-a two- dimensional closed intersecting lines- figure made up of lines that meet or parallelogram-a straight line segments. cross quadrilateral with both pairs of opposite sides parallel. line segment-a finite portion of a line , often isosceles triangle-a denoted by its end triangle having two points polyhedron-a three- sides, called the legs, dimensional closed of equal length pentagon- a polygon figure made up of with five sides faces that are all net- a blueprint, or polygons pattern, for a three dimensional model.

4 Prism- a three- dimensional figure perpendicular lines- with parallelogram kite-a quadrilateral lines in the same faces and two parallel, with two pairs of obtuse angle-an angle plane which intersect congruent bases adjacent sides with measuring between 90 to form a right angle. equal lengths. and 180 degrees . pyramid- a geometric rectangular prism- a rhombus- a similar-two or more solid with a base that three-dimensional quadrilateral in which figures having the is a polygon and all figure with all sides have the same shape but not other faces are parallelogram faces same length necessarily the same triangles with a and two parallel, size common vertex congruent rectangular bases. right angle- an angle measuring 90 degrees quadrilateral-a rectangular slide- see translation polygon with four pyramid- a geometric sides solid with a base that is a rectangle and all solid figure- a closed, other faces are three dimensional triangles with a figure common vertex rotation (turn)- a radius-the distance transformation sphere-the set of all from the center of a obtained by rotating a points in three- circle to any point on figure around a fixed dimensional space its edge; half a point ( , turning a that are located at a diameter figure about a point).

5 Given distance from reflection (flip)-a the center transformation which produces the mirror image of a figure ( , . flipping a figure ray-a portion of a line across a line ) square- a regular extending in one scalene- a polygon is quadrilateral (all sides direction from a point scalene if its sides are and angles are all different lengths congruent). rectangle-a quadrilateral in which regular polygon- a all the angles have the polygon in which all symmetry- a figure same measure (90 angle and all sides are side- a line segment at has symmetry if there degrees) congruent; examples- the boundary of a exists some line or equilateral triangle, polygon point through which square, regular all points of the figure octagon can be reflected to generate another point on the figure tessellation- covering triangular prism- a of the plane, three-dimensional sometimes referred to figure with as a tiling, referring to parallelogram faces the way that tiles and two parallel, cover a floor congruent triangular bases.

6 Three-dimensional- an object that has triangular pyramid - length, width, and a geometric solid with height a base that is a triangle and all other transformation- a faces are triangles rule for moving every with a common vertex point in a plane figure to a new location translation (slide)- a transformation that slides a figure a given . turn- see rotation distance in a given direction two-dimensional- a figure that has length and width but not height ( , a plane figure such as a rectangle or circle). vertex (vertices)- the trapezoid (inclusive) points where two line - a quadrilateral with segments come at least one set of together (corner parallel sides. triangle- a polygon with three sides)