Geometry Vocabulary

Across

3. A form of the equation of a line written as y = mx + b, where m is the slope and b is the y-intercept.
5. The ratio of the vertical change (rise) to the horizontal change (run) between any two points on a line.
7. A polygon with three sides.
8. A polygon with all sides congruent and all angles congruent.
10. The line across which a reflection occurs.
11. A triangle with one right angle (90°).
16. An angle whose vertex is at the center of a circle.
18. A proposition that is believed to be true but has not been proven.
20. The ratio of a length in the image to the corresponding length in the pre-image under a dilation.
25. A parallelogram with all sides congruent.
26. A portion of a line consisting of one point, called the endpoint, and all points on the line on one side of the endpoint.
28. A portion of the circumference of a circle.
29. A polygon with four sides.
30. A formula used to find the distance between two points in the coordinate plane: d = √[(x₂ - x₁)² + (y₂ - y₁)²].
32. A flat surface of a polyhedron.
34. A transformation that flips a figure across a line.
35. Two angles that share a common vertex and side, but have no common interior points.
38. A line segment with endpoints on a circle.
39. A three-dimensional figure whose surfaces are polygons.
43. The ratio of the adjacent side to the hypotenuse in a right triangle.
45. Lines in the same plane that never intersect.
47. Two angles whose measures sum to 90°.
49. A triangle in which all angles are acute (less than 90°).
50. The original figure before a transformation.
52. The y-coordinate of the point where a line crosses the y-axis.
54. A line that intersects a circle at exactly two points.
57. A three-dimensional figure with a circular base and a curved surface that tapers to a point (vertex).
58. A quadrilateral with opposite sides parallel and congruent.
60. A quadrilateral with exactly one pair of parallel sides.
61. A formula used to find the coordinates of the midpoint of a line segment: ((x₁ + x₂)/2, (y₁ + y₂)/2).
63. An angle that measures exactly 90°.
64. The amount of space occupied by a three-dimensional figure.
65. A closed plane figure made up of straight line segments.
67. An angle that measures less than 90°.
69. A transformation that slides a figure without rotation or reflection.
70. A parallelogram with four right angles.
71. A logical argument that establishes the truth of a statement.
72. A portion of a line consisting of two points, called endpoints, and all points between them.
73. A statement accepted as true without proof (same as axiom).
77. Angles that appear in the same relative position when a transversal intersects two lines.
78. The x-coordinate of the point where a line crosses the x-axis.
79. Points or lines that lie in the same plane.
80. A rectangle with all sides congruent.
81. A three-dimensional figure with two parallel, congruent circular bases and a curved surface.
82. An angle with its vertex on a circle and sides that contain chords of the circle.
83. A triangle with no sides congruent.

Down

1. Having the same size and shape.
2. An angle that measures exactly 180°.
4. A polygon with eight sides.
6. A triangle with all sides congruent.
9. Lines that intersect to form right angles.
12. The ratio of the opposite side to the adjacent side in a right triangle.
13. A ray that divides an angle into two congruent angles.
14. A region of a circle bounded by an arc and two radii.
15. Two angles whose measures sum to 180°.
17. A straight set of points that extends infinitely in opposite directions.
19. A polyhedron with a polygonal base and triangular faces that meet at a common vertex.
21. The distance around a circle.
22. A line segment from the center of a circle to any point on the circle.
23. A regular polyhedron with six congruent square faces.
24. A line segment connecting a vertex of a triangle to the midpoint of the opposite side.
27. An angle that measures greater than 90° but less than 180°.
31. An example that disproves a statement.
33. A polygon with six sides.
36. A figure formed by two rays sharing a common endpoint (vertex).
37. A line that intersects a circle at exactly one point.
40. The set of all points in a plane that are at a fixed distance (radius) from a fixed point (center).
41. A transformation that changes the size of a figure but not its shape.
42. A statement that has been proven to be true.
44. The set of all points in three-dimensional space that are at a fixed distance (radius) from a fixed point (center).
46. The ratio of the opposite side to the hypotenuse in a right triangle.
48. A line that intersects two or more lines.
51. A triangle with at least two sides congruent.
53. statement - A statement of the form "if p, then q."
55. The common endpoint where two or more line segments, lines, or rays meet.
56. Having the same shape but not necessarily the same size.
58. The distance around a two-dimensional shape.
59. A triangle with one obtuse angle (greater than 90°).
62. A plane with a coordinate system in which the coordinates of a point are its distances from two fixed perpendicular lines called the x-axis and y-axis.
66. A location in space that has no size or dimension.
68. A line segment where two faces of a polyhedron meet.
71. A polyhedron with two parallel, congruent faces (called bases) and rectangular lateral faces.
74. A polygon with five sides.
75. A transformation that turns a figure about a fixed point.
76. A line segment that passes through the center of a circle and has endpoints on the circle.