Week 10 Flashcards
Reflection symmetry with respect to a plane (3D) (also called mirror-image symmetry or plane symmetry)
A reflection in a plane that gives the original shape as the image
Plane of symmetry
Plane used in reflection symmetry - gives a cross-section of a shape
Reflection line
2D rigid motion in which a point on either side of the line has its image at thought the line were a mirror
Rotation about a point
2D rigid motion in which the plane is turned about a point called the center of the rotation
Rotational symmetry with respect to a point (2D) or with respect to a line (3D)
A rotation such that the image is the same as the original shape
Symmetry
A mapping of an object (called original) to another object (called image) that preserves size, shape, and position as original
Identity symmetry
Each point remains in place (ie. a 360 rotation would result in the identity symmetry)
Reflection symmetry (2D)
An object is reflected about a straight line (called line of reflection) resulting in an object appearing identical to the original object
Coterminal angles
Angles that share the same final position after a rotation
A regular n-gon has exactly n lines of reflection T/F
True
Depth
The horizontal distance from back to front
Width
The horizontal distance from left to right
Height
The vertical distance from top to bottom
Surface area
The sum of the areas of the polyhedron’s faces
Volume
The 3D space enclosed by the polyhedron’s faces
Center of the rotational symmetry
The fixed point about which a shape is rotated such that rotational symmetry holds
Symmetry of a shape
Any movement or geometric transformation that fits the shape onto the same set of points it started with
