Pre-Algebra Unit 1B: Geometry Flashcards

Angles

• Acute Angle: Less than 90 degrees but more than 0 degrees.
• Adjacent Angles: Share a common side and vertex.
• Complementary Angles: Two angles that sum to 90 degrees.
• Obtuse Angle: Measures more than 90 degrees but less than 180 degrees.
• Right Angle: Measures exactly 90 degrees.
• Straight Angle: Measures exactly 180 degrees and forms a straight line.
• Supplementary Angles: Two angles whose sum is 180 degrees.
• Vertex: Point where two line segments, lines, or rays meet, forming an angle.
• Vertical Angles: Opposite congruent angles formed by intersecting lines.

Line Relationships

• Perpendicular Lines: Intersecting lines that form right angles.
• Alternate Interior Angles: On opposite sides of a transversal, within the lines.
• Corresponding Angles: Same position on two different parallel lines cut by a transversal.
• Parallel Lines: Lines that do not intersect and are in the same plane.
• Transversal: A line that intersects two or more lines in a plane at different points.
• Alternate Exterior Angles: Outside the lines, on opposite sides of a transversal.

Shapes and Polygons

• Polygon: Closed figure formed by three or more line segments.
• Triangle: A three-sided polygon, including:
  • Acute Triangle: Three acute angles.
  • Equilateral Triangle: Three congruent sides.
  • Isosceles Triangle: Two equal sides.
  • Obtuse Triangle: One angle greater than 90 degrees.
  • Right Triangle: Contains a 90 degree angle.
  • Scalene Triangle: No equal sides.
• Quadrilateral: A four-sided polygon, including:
  • Parallelogram: Two pairs of parallel sides.
  • Rectangle: Four right angles and two pairs of congruent, parallel sides.
  • Rhombus: All sides congruent.
  • Square: Four congruent sides and four right angles.
  • Trapezoid: One pair of parallel sides.

Higher-Dimensional Polygons

• Pentagon: Five-sided polygon.
• Hexagon: Six-sided polygon.
• Heptagon: Seven-sided polygon.
• Octagon: Eight-sided polygon.
• Nonagon: Nine-sided polygon.
• Decagon: Ten-sided polygon.
• Dodecagon: Twelve-sided polygon.

Transformations

• Congruent: Figures having the same size and shape.
• Similar: Figures that share the same shape but not necessarily size.
• Transformations: Changes in position or size of a geometric figure, includes:
  • Reflection: Flips a figure over a mirror line.
  • Rotation: Rotates around a point.
  • Translation: Slides each point of a figure the same distance in the same direction.

Circle Measurements

• Chord: Line segment between any two points on a circle.
• Diameter: Straight line that passes through the center of a circle, connecting two points on its circumference.
• Circumference: The distance around a circle.
• Area: The measure, in square units, of the inside of a plane figure.
• Diagonal: A straight line through a figure from one corner to another.