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1-4: Angles Vocabulary

Terms in this set (14)

Angle
A figure formed by two rays with a common endpoint.
Sides of an Angle
The 2 rays that make up the angle.
Vertex of an Angle
The common endpoint of the 2 rays that are the sides of an angle.
Straight Angle
An angle that measures 180 degrees.
Right Angle
An angle that measures 90 degrees.
Acute Angle
An angle that measures less than 90 degrees but more than 0 degrees.
Obtuse Angle
An angle that measures more than 90 degrees but less than 180 degrees.
Protractor Postulate
1. On line AB in a given plane (given starting line to build protractor)
2. Choose any point O between A & B. (create the vertex of all angles to be measured)
3. Consider ray OA & ray OB & all the rays that can be drawn from O on 1 side of line AB. (create all possible sides of angles to form all possible angles less than or = to 180 degrees)
4. These rays can be paired with the real numbers 0 to 180 in such a way that:
A. Ray OA is paired with 0, & ray OB with 180. (create a scale)
B. If ray OP is paired with x, & ray OQ with y, them m<POQ = |x-y|. (create specific measurements)
Angle Addition Postulate
A. If point B lies in the interior of <AOC then m<AOB+m<BOC=m<AOC.
B. If <AOC is a straight < & B is any point NOT on line AC, then m<AOB+m<BOC=180.
Congruent Angles
Angles that have = measures.
m<R=m<S (focus on measurement or degrees)
<R congruent <S (focus on shape)
Adjacent Angles
Two angles IN A PLANE that have a common vertex & a common side but no common interior points.
Angle Bisector
A ray that divides an angle into 2 congruent adjacent angles.
What can you always conclude from any diagram (if definitions are met)? 7 of them.
1. All points shown are coplanar.
2. Lines & rays intersect at a point.
3. 3 points on a line are collinear.
4. A point is "between" 2 other points.
5. An angle is a straight angle.
6. A point is in the interior of an angle.
7. 2 angles are adjacent.
What must you show in a diagram? 2 of them.
1. To show congruent angles or sides (segments), use congruent marks.
2. To show a right <, use a square.
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