Geometry

• Point - Has an exact location and has no dimension, usually represented by a small dot ( • )

  A• <- This is called point A
• Line - Consists of infinite number of points and externals in opposite direction, represented by a straight line with crossheads to indicate that the line extends without end in two dimensions.
• Plane - A flat surface and extends in 2 dimensions
• Collinear - Points that lie on the same line
• Coplanar - Points that lie on the same plane
• Line Segment - Is a set of points, which is the union of two distinct points of a line and all points of line, between them.

  The given line segment is read as: “AB”

  
• Ray - It has only one endpoint and extends indefinitely in one direction.

  The given figure ray is read as: “Ray AB”

  
• Opposite Rays - Are two distinct rays that have the same vertex and which lie on the same line.

  The given figure is read as; “Ray UT and Ray TV”

  Where T is the given vertex point between U,V.

  
• Angles - These are two non-collinear rays that have a common endpoint.

  To name an angle, the angle can be; ∠ABC or ∠B where B is the vertex of the angle.
• Interior Portion - These are the points inside the angle.

  Exterior Portion -These are the points outside the angle.
• Protractor - This is the tool used to measure angles.
• Degree (°) - This is the unit used for angles
• 90° - Right Angle

  
• 0°/180° - Straight Angle

  
• Acute Angle - Any angle that measures less than 90 degrees

  
• Obtuse Angle - Greater than 90 degrees but less than 180 degrees

  
• Congruent Angle - These are two angles that have the same measurement.
• Adjacent Angles - Are two angles that have a common vertex and a common side.
• Vertical Angles - Are angles formed by two lines intersecting at a point. They are opposite to each other.

  • Vertical angles are congruent.
• Supplementary Angles - Are angles whose sum is exactly 180 degrees.
• Complementary Angles - Are two angles whose sum is exactly 90 degrees.
• Linear Pairs - A linear pair is a pair of adjacent, and supplementary angles.
• Parallel Lines - Are two lines that never meet.

  The given figure is read as; “A||B”

  
• Perpendicular Lines - Are two lines that form a right angle.

  
• Transversal - A line which intersects two coplanar parallel lines at two different points.

  Given A||B;

  By color coded, which red implies the exterior portion, while green implies the interior portion.

  
• Exterior Angles - Are angles found outside the two parallel lines and on both sides of the transversal.

  Interior Angles - are angles found inside the two parallel lines.

  
• Corresponding Angle - Are non-adjacent angles, one interior, and another exterior, found on the same side of the transversal.