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43 terms

Chapter 8 Math Definitions

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straight angle
an angle whose measure is exactly 180 degrees
right angle
an angle whose measure is exactly 90 degrees (we place a "block" at the vertex of the angle)
complementary
the sum of two angles is 90 degrees
supplementary
the sum of two angles is 180 degrees
vertical angles
angles that are across from each other in an "x" pattern (equal to each other in measure)
perpendicular lines
2 lines that intersect at a right angle
corresponding angles
angles that are in the same place in the top "x" as in the bottom "x"
congruent
when two angles are the same size, but we don't care about the angle measure
alternate interior angles
angles that are on the opposite sides of the line "t" and are inside the parallel lines
alternate exterior angles
angles that are outside of the parallel lines and are on opposite sides of line "t"
acute triangle
a triangle that has 3 acute angles
right triangle
a triangle that has one right angle
obtuse triangle
a triangle that has one obtuse angle
equilateral triangle
a triangle that has 3 sides of equal length
isosceles triangle
a triangle that has 2 or more sides with the same length
scalene triangle
a triangle that has no sides of the same length
quadrilateral
a closed figure with four sides that are line segments
trapezoid
a quadrilateral with exactly one pair of parallel sides
parallelogram
a quadrilateral with two pairs of parallel sides
rhombus
a parallelogram with 4 sides of equal length
rectangle
a parallelogram with 4 right angles
square
a parallelogram with 4 sides of equal length and 4 right angles
diagonal
a segment that joins two vertices of a quadrilateral, but is not a side
polygon
a closed figure that's made up of 3 or more line segments that intersect only at their endpoints
regular polygon
a polygon with all sides equal in length and all angles equal in measure
sum of interior angles
(n-2) * 180
measure of each interior angle
(n-2) * 180/n
Side-Side-Side (SSS)
If 3 sides of 1 triangle are congruent to 3 sides of another triangle, then the triangles are congruent
Side-Angle-Side (SAS)
If 2 sides and the angle between them (known as the "included angle") are congruent to 2 sides and the angle between them in another triangle, then the triangles are congruent
Angle-Side-Angle (ASA)
If 2 angles and the side between them (known as the "included side") in 1 triangle are congruent to 2 angles and the side between them in another triangle, then the triangles are congruent
reflection
a transformation that creates a mirror image of a figure
line of reflection
a line where the figure is reflected
transformation
a geometrical operation that change a figure into another figure
line symmetry
1 half of the figure is a mirror image of the other half folded over this line
image
the new figure created after a figure is transformed
translation
a transformation that slides a figure
coordinate notation
describes the transformation in terms of changes to the coordinates of the points in the figure
rotation
a transformation that turns each point of a figure the same number of degrees around a common point
angle of rotation
the angle through which a figure is rotated
center of rotation
the common point of the rotation's center
similar polygons
polygons that have the same shape, but are not necessarily the same size
scale factor
the ratio of corresponding sides of 2 polygons
dilation
a transformation that stretches or shrinks a figure