Geometry Basic Vocabulary

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Geometry Basic Vocabulary
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Point

• A point marks an exact location in space.
• It has no size. It is infinitely small.
• Use a capital print letter to name a point.

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Line

• A line is an endless straight path.
• It is the infinitely straight arrangement of
  points.
• Use any two points on the line to name the line.

AG or GA or JG or AJ
J
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Line Segment

• A line segment is part of a line between two
  endpoints.
• Use the two endpoints to name the line segment.

AG or GA
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Ray

• A ray is part of a line that has one endpoint and
  goes on forever in one direction.
• Use the endpoint and one other point on the ray
  to name a ray. Endpoint first. ALWAYS!

Ray GA Or GA
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Plane

• A plane is an endless flat surface.
• Use three points that are not on a line to name
  the plane or the capital cursive letter in the
  corner.

Plane GFH Or Plane B
B
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Angle

• An angle is formed by two rays with the same
  endpoint.
• An angle can be named by three letters a point
  from each side and the vertex as the middle
  letter.
• If there are no other angles at the vertex, it
  can also be named by a single letter, its vertex.

ltGFH or ltF
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Right Angle

• A right angle measures 90

blue box indicates a right angle
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Acute Angle

• An acute angle is greater than 0 and less than
  90

60
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Obtuse Angle

• An obtuse angle is greater than 90 and less than
  180

140
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Straight Angle

• A straight angle measures 180.
• Also known as a line.

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Intersecting Lines

• Intersecting lines are lines that cross at one
  point.

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Parallel Lines

• Parallel lines are lines in a plane that never
  intersect and are the same distance apart at
  every point.

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Perpendicular Lines

• Perpendicular lines are lines that intersect to
  form four right angles.