Geometry - Middle School

If you feel obtuse when it comes to angles, review this list of geometry terms. You'll learn about planes, polygons, perimeter, and more. It's as easy as pi!
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Full list of words from this list:

words only definitions & notes
  1. acute
    (of an angle) less than 90 degrees
  2. acute angle
    an angle less than 90 degrees but more than 0 degrees
  3. adjacent
    having a common boundary or edge
  4. angle
    the space between two lines or planes that intersect
  5. arc
    a continuous portion of a circle
  6. area
    the extent of a two-dimensional surface within a boundary
  7. base
    the bottom side of a geometric figure
  8. center
    a point equidistant from the ends of a line
  9. circle
    a plane curve with every point equidistant from the center
  10. circumference
    the length of the closed curve of a circle
  11. clockwise
    in the direction that the hands of a clock move
  12. complementary angles
    two angles whose sum is a right angle
  13. compose
    form the substance of
  14. cone
    a shape with a circular base and sides tapering to a point
  15. congruent
    coinciding when superimposed
  16. coordinate
    a number that identifies a position relative to an axis
  17. coordinate system
    a system that uses coordinates to establish position
  18. counterclockwise
    in a direction opposite to the direction in which the hands of a clock move
  19. cube
    a three-dimensional figure with six equal squares as faces
  20. cylinder
    a solid bounded by a round surface and two parallel planes
  21. decompose
    separate into constituent elements or parts
  22. degree
    a measure for arcs and angles
  23. diameter
    the length of a straight line through the center of a circle
  24. dimension
    the magnitude of something in a particular direction
  25. equation
    a mathematical statement that two expressions are the same
  26. equilateral triangle
    a three-sided regular polygon
  27. exterior angle
    the supplement of an interior angle of a polygon
  28. face
    a surface forming part of the outside of an object
  29. formula
    a group of symbols that make a mathematical statement
  30. height
    distance from the base of something to its top
  31. hexagon
    a six-sided polygon
  32. hypotenuse
    the side of a right triangle opposite the right angle
  33. inscribe
    carve, cut, or etch into a material or surface
  34. interior angle
    the angle inside two adjacent sides of a polygon
  35. intersect
    meet or cross at a point; overlap
  36. isosceles
    (of a triangle) having two sides of equal length
  37. isosceles triangle
    a triangle with two equal sides
  38. length
    the linear extent in space from one end to the other
  39. line
    a length between two points
  40. obtuse
    of an angle, between 90 and 180 degrees
  41. obtuse angle
    an angle between 90 and 180 degrees
  42. origin
    the point of intersection of axes on a coordinate plane
  43. parallel
    being everywhere equidistant and not intersecting
  44. parallelogram
    a quadrilateral whose opposite sides are parallel and equal
  45. partition
    divide into parts, pieces, or sections
  46. perimeter
    a line enclosing a plane area
  47. perpendicular
    intersecting at or forming right angles
  48. pi
    the ratio of the circumference to the diameter of a circle
  49. plane
    an unbounded two-dimensional shape
  50. plane section
    the area created by a plane cutting through a solid
  51. point
    a geometric element that has position but no extension
  52. polygon
    a closed plane figure bounded by straight sides
  53. prism
    a polyhedron with two congruent and parallel faces
  54. proof
    a formal series of statements showing that something is true
  55. protractor
    drafting instrument used to draw or measure angles
  56. pyramid
    a polyhedron having a polygonal base and triangular sides
  57. quadrant
    any of the four areas into which a plane is divided
  58. quadrilateral
    a four-sided polygon
  59. radius
    the length of a line between a circle's center and perimeter
  60. ray
    (mathematics) a straight line extending from a point
  61. rectangle
    a parallelogram with four right angles
  62. rectangular
    having four right angles
  63. reflection
    transformation in which the direction of an axis is reversed
  64. rhombus
    a parallelogram with four equal sides
  65. right angle
    the 90 degree angle between two perpendicular lines
  66. right triangle
    a triangle with one right angle
  67. rotation
    a transformation in which the coordinate axes are turned
  68. scale
    the ratio between the size of a thing and its representation
  69. scalene
    having three sides of different lengths
  70. scalene triangle
    a triangle with no two sides of equal length
  71. sequence
    serial arrangement in which things follow in logical order
  72. sphere
    a solid figure bounded by a round surface
  73. square
    a polygon with four equal sides and four right angles
  74. surface area
    the extent of a 2-dimensional surface enclosed within a boundary
  75. symmetry
    exact reflection of form on opposite sides of a line
  76. three-dimensional
    involving or relating to three dimensions or aspects
  77. translation
    when the coordinate system origin moves to another position
  78. transversal
    extending or lying across
  79. trapezoid
    a quadrilateral with one pair of parallel sides
  80. triangle
    a three-sided polygon
  81. two-dimensional
    involving measurements of magnitude in two directions
  82. vertex
    the point of intersection of lines
  83. volume
    the amount of 3-dimensional space occupied by an object
  84. x-axis
    the horizontal axis in a plane coordinate system
  85. y-axis
    the vertical axis in a plane coordinate system
Created on Thu Feb 09 13:21:33 EST 2017 (updated Wed Mar 29 15:53:29 EDT 2017)

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