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Whitney Geometry
| Question | Answer |
|---|---|
| acute triangle | A triangle in which all three angles are acute Examples: |
| angle | A figure formed by two rays that have a common endpoint Example: |
| chord | A line segment with its endpoints on a circle Example: |
| circle | A closed plane figure with all points on the figure the same distance from the center Example: |
| circumference | The distance around a circle Example: |
| closed figure | A figure that begins and ends at the same point Examples: |
| cone | A solid figure that has a circular base and one vertex Examples: |
| congruent | Having the same size and shape Example: The triangles are congruent. |
| congruent figures | Figures that have the same size and shape Example: The triangles are congruent. |
| coordinate plane | A plane formed by two intersecting and perpendicular number lines called axes Example: |
| coordinates | The numbers in an ordered pair Example: |
| cube | A solid figure with six congruent square faces Examples: |
| cylinder | A solid figure that has two parallel bases that are congruent circles Examples: |
| degree (°) | A unit for measuring angles and temperature Examples: |
| diamete | A line segment that passes through the center of a circle and has its endpoints on the circle Example: diameter |
| dimension | A measure in one direction; the length, width, or height of a figure |
| edge | The line segment where two faces of a solid figure meet Example: edge |
| equilateral triangle | A triangle with three congruent sides Example: |
| face | A polygon that is a flat surface of a solid figure Example: face |
| figurate numbers | Numbers that can be represented by geometric figures Examples: |
| hexagon | A polygon with six sides and six angles Examples: |
| hypotenuse | In a right triangle, the side opposite the right angle; the longest side in a right triangle Example: hypotenuse |
| intersecting lines | Lines that cross at exactly one point Example: Line EF intersects line GH. |
| isosceles triangle | A triangle with two congruent sides Example: |
| line | A straight path in a plane that goes on forever in opposite directions Example: line AB or line BA |
| line segment | A part of a line that includes two points, called endpoints, and all of the points between them Example: line segment AB or line segment BA |
| line symmetry | A figure has line symmetry if a line can separate the figure into two congruent parts Example: |
| obtuse angle | An angle whose measure is greater than 90° and less than 180° Example: |
| obtuse triangle | A triangle that has one obtuse angle Example: |
| octagon | A polygon with eight sides Examples: |
| ordered pair | A pair of numbers used to locate a point on a coordinate plane; the first number tells how far to move horizontally and the second number tells how far to move vertically Example: (1,2) represents 1 unit to the right of zero and 2 units up. |
| parallel lines | Lines in a plane that never intersect Example: |
| parallelogram | A quadrilateral whose opposite sides are parallel and congruent Examples: |
| pentagon | A polygon with five sides Examples: |
| perpendicular lines | Two lines that intersect to form four right angles Example: |
| (noun) | The ratio of the circumference of a circle to its diameter An approximate decimal value of pi is 3.14. |
| plane | A flat surface that extends without end in all directions Example: Planes are named by three points in the plane |
| plane figure | A figure which lies in a plane Examples: |
| point | An exact location in space, usually represented by a dot Example: point A |
| When a figure can be turned half way about a central point and still look the same Example: | |
| polygon | A closed plane figure formed by three or more line segments Examples: |
| polyhedron | A solid figure with flat faces that are polygons Examples: |
| prism | A solid figure that has two congruent, polygon-shaped bases, and other faces that are all rectangles Examples: rectangular prism triangular prism |
| protractor | A tool used for measuring or drawing anglesExample: |
| pyramid | A solid figure with a polygon base and all other faces triangles that meet at a common vertex Example: This is a square pyramid. |
| quadrilateral | A polygon with four sides Examples: |
| radius | A line segment with one endpoint at the center of a circle and the other endpoint on the circle Example: radius |
| ray | A part of a line, with one endpoint, that continues without end in one direction Example: ray CD |
| rectangle | A parallelogram with four right angles Example: |
| rectangular prism | A solid figure in which all six faces are rectangles Example: |
| reflection (flip) | A movement of a figure to a new position by flipping it over a line Example: |
| regular polygon | A polygon in which all sides are congruent and all angles are congruent Examples: |
| rhombus | A parallelogram with four congruent sides Example: |
| right angle | An angle formed by perpendicular lines, line segments, or rays and with a measure of 90° Example: |
| right triangle | A triangle with one right angle Example: |
| rotation (turn) | A movement of a figure by turning it around a fixed point Example: |
| rotational symmetry | The property of a figure that can be rotated less than 360° around a central point and still be congruent to the original figure Example: |
| scale drawing | A drawing that shows a real object smaller than (a reduction) or larger than (an enlargement) the real object Example: |
| scalene triangle | A triangle with no congruent sides Example: |
| similar figures | Figures with the same shape but not necessarily the same size Example: |
| solid figure | A three-dimensional figure Examples: sphere cube |
| sphere | A solid figure that has the shape of a round ball; all points are the same distance from the center Example: |
| square | A rectangle with 4 equal sides Example: |
| square pyramid | A pyramid with a square base and four triangular faces Example: |
| tangram | A puzzle consisting of seven polygon-shaped pieces that can be rearranged to make various figures or shapes Example: |
| tessellation | An arrangement of closed figures that completely covers a surface with no gaps and no overlaps Example: |
| three-dimensional | Measured in three directions, such as length, width, and height Example: heightwidth lengthThe rectangular prism is a three-dimensional figure. |
| transformation | The movement of a figure by a translation, reflection, or rotation Examples: translationreflectionrotation |
| translation (slide) | A movement of a figure along a straight line Example: |
| trapezoid | A quadrilateral with one pair of parallel sides Examples: |
| triangle | A polygon with three sides Examples: |
| triangular number | A number that can be represented by a triangular array Examples: |
| two-dimensional | Measured in two directions, such as length and width Example: widthlength |
| vertex | The point where two or more rays meet; the point of intersection of two sides of a polygon; the point of intersection of three or more edges of a solid figure; the top point of a cone; the plural of vertex is vertices Examples: |
| volume | The measure of the amount of space a solid figure occupies Example: The volume of this figure is 24 cubic units |
| x-axis | The horizontal number line on a coordinate plane Example: |
| x-coordinate | The first number in an ordered pair, which tells the distance to move right or left from (0, 0) Example: |
| y-axis | The vertical number line on a coordinate plane Example: |
| y-coordinate | The second number in an ordered pair, it tells the distance to move up or down from (0, 0) Example: |
| Circumference | C = x d |
| Volume of rectangular prism | V = l x w x h |
| Perimeter of polygon | = sum of lengths of sides |
| Perimeter of rectangle | P = (2 x l) + (2 x w) |
| Perimeter of square | P = 4 x s |
| Area of rectangle | A = l x w |
| Area of parallelogram | A = bh |
| Area of triangle | A = bh |