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Level 427

Angles


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Exterior Angle of a Polygon
an angle that forms a linear pair with one of the angles of the polygon.
Remote Interior Angles of a Triangle
the two angles non-adjacent to the exterior angle.
Linear Pair Postulate
If two angles form a linear pair, then they are supplementary.
Vertical Angle Theorem
If two angles are vertical angles, then they are congruent. (p. 127)
Triangle Angle-Sum Theorem
The sum of the measures of the angles of a triangle is 180°.
Isosceles Triangle Theorem
If 2 sides of a triangle are congruent, then the angles opposite those sides are congruent
Converse of the Isosceles Triangle Theorem
If 2 angles of a triangle are congruent, then the sides opposite those angles are congruent.
Exterior angle theorem
The measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles.
Adjacent Angles
Angles that are next to each other. They share a vertex and a common side.
Midpoint
if a line segment has a midpoint, then the 2 segments formed are congruent
right angle
An angle that is 90 degrees (It makes a square in the corner).
straight angle
An angle that measures 180 degrees
Acute Angle
An angle that measures LESS than 90 degrees.
Angle
Two rays with the same end point.
Bisector
if a line bisects a line segment, then it intersects it at its midpoint
Complementary Angles
The sum of the measure of two angles is 90 degrees.
Congruent
A plane figure with the same size and shape.
equiangular
3 equal angles
equilateral
all sides have the same length
Linear pair
A pair of adjacent angles whose non-common sides are opposite rays.
Obtuse Angle
An angle that measures MORE than 90 degrees
Supplementary Angles
The sum of the measure of two angles is 180 degrees.
Vertical Angles
Angles opposite one another when two lines intersect.
Segment Addition Postulate
If A, B, and C are collinear, then point B is between A and C if and only if AB + BC = AC.
Angle Addition Postulate
D is in the interior of angle ABC and only if m<ABD + m<DBC = m<ABC.
Complimentary Angles
Angles whose measure adds up to 90 degrees.
vertex
The point where two sides meet. (Shared end points of the line segments of a polygon.)
Congruent Angles
Angles with equal measures are..
Scalene Triangle
A triangle with no congruent sides
equilateral triangle
Triangle with a 90° angle
isosceles triangle
Triangle with 2 equal sides and 2 equal angles.
degrees
a unit for measuring angles
Protractor
A tool used to measure angles
degree
the highest power of a polynomial
Sides
The angle bisectors of a triangle intersect at a point that is equidistant from all of "these" of the triangle
triangle
P=a+b+c
Quadrilateral
A polygon with 4 sides and 4 angles.
pentagon
a 5 sided polygon
octagon
an 8-sided polygon
decagon
a 10-sided polygon
Right Triangle
A triangle with one right angle.
alternate interior angles
Angles that lie within a pair of parallel lines and on opposite sides of a transversal; congruent
Angle Bisector
A segment or Ray that cuts an < into two ️congruent <'s
angle of rotation
formed by rays drawn from the center of rotation to a point and its image
arc
part of a circle
Center of Rotation
point around which a figure rotates
Central Angle
an angle whose vertex is the center of the circle
Circle
r= asin(theta)
Complementary
Two angles whose sum is 90 degrees.
congruent figures
The SAME SIZE and SAME SHAPE
corresponding angles
Angles that have the same relative positions in geometric figures.
image
the resulting figure AFTER a transformation is performed on it
Line
A straight path that goes without end in two directions.
line of reflection
The line over which a figure is reflected. The vertices of the original and new figure are the same distance from this. The line of reflection can be the x-axis, the y-axis, or any line on the coordinate plane.
line of symmetry
The line that divides two matching parts. It can be vertical, horizontal, or diagonal.
major arc
larger than a semicircle; named by its endpoints and another point between the endpoints on the arc with an arc symbol over the letters - ⌒
parallel lines
2 lines that never cross/intersect and stay the same distance apart
Perpendicular Bisector
A segment or Ray the perpendicularly bisects a side of a 🔺
Perpendicular lines
lines in a plane that intersect to form 4 right angles
plane
A flat surface.
point
an exact location in space
polygon
a closed figure made by joining line segments where each line segment intersects exactly 2 others
ray
Part of a line that has one end point and goes in one direction without end.
reflection
It is a transformation that flips a figure over a line of reflection.
Reflectional Symmetry
A figure that can be reflected over a line so its image matches the original figure.
regular polygon
a convex polygon in which all sides and angles are congruent
rotation
It is a transformation that turns a figure about a fixed point.
Rotational Symmetry
If you can rotate (or turn) a figure around a center point by fewer than 360° and the figure appears unchanged, then the figure has rotation symmetry.
segment
A part of a line between two endpoints.
Segment Bisector
A segment that divides another segment into two congruent pieces.
semicircle
half of a circle
skew
they have no relationship
Supplementary
Angles that add to 180 degrees.
Transformation
a movement on the cartesian plane
translation
It is a transformation that moves points the distance and in the same direction.
transversal
A line that intersects two or more lines.
Alternative Angles
Interior angles on the alternate sides of the transversal they are both equal in size.
Co-interior angles
Angles that are both inside the parallel lines and on the same side of the transversal are supplementary.