Back to Unit 9


Angle Relationships
 

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Terms:

Ray: part of a line that starts at an endpoint and goes on forever in one direction.
Two points on it identify a ray. Always name the endpoint first.
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The symbol for a ray is an arrow above the two points - MN


Angle: figure formed by two rays with a common endpoint called a vertex
It can be identified three ways: <EDF, <FDE, or <D (Note the letter of
the vertex is always in the middle)

Vertex: The common endpoint where two rays meet to form an angle


Degree: unit of measure that is of a complete turn (circle)

Right angle: angle whose measure is equal to 90.

Straight angle: angle whose measure is equal to 180 (A straight line).

Acute angle: angle whose measure is greater than 0 but less than 90.

Obtuse angle: angle whose measure is greater than 90 but less than 180.

Supplementary angle: Two angles are supplementary angles if the sum of the measures of the angles is 180. (Add up to a straight line (S for Straight))

<XYZ and <ZYW are supplementary




Complementary angles: Two angles are complimentary angles if the sum of the measures of the angles is 90. (C for Corner)

<ABC and <DBC are complementary


 

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