Download Chapter 12 Two-Dimensional Shapes

plane shape
• A shape in a plane that is formed by
curves, line segments, or both.
These are some plane figures
12.1
point
An exact position or location
.
point
12.1
line
• A straight path extending in both
directions with no endpoints
Example:
12.1
endpoints
• Points that are used to show segments
of lines.
Example:
12.1
line segment
• A part of a line that includes two points,
called endpoints, and all the points
between them
Example:
12.1
ray
• A part of a line, with one endpoint, that
is straight and continues in one
direction.
Example:
12.1
two-dimensional shape
• A shape that lies in a plane; a shape
having length and width.
Example:
12.1
closed shape
• A shape that begins and ends at the
same point.
Examples:
12.1
Open shape
• A shape that does not begin and end
at the same point.
Examples:
12.1
angle
• A figure formed by two rays or line
segments that share an endpoint.
Example:
12.2
vertex
• The point at which two rays of an angle
or two (or more) line segments meet in a
plane figure or where three or more
edges meet in a solid figure
Example:
12.2
right angle
• An angle that forms a square corner
Example:
12.2
acute angle
• An angle that has a measure less than a
right angle.
Example:
obtuse angle
• An angle that has a measure greater
than a right angle.
Example
straight angle
• An angle in which two rays point in
opposite directions so that they form a
line
Example:
polygon
• A closed plane figure with straight
sides that are line segments.
Examples:
12.3
side
• a line segment of a polygon
Example:
This polygon has 4 sides
12.3
triangle
• A polygon with three sides and three
angles.
Examples:
12.3
quadrilateral
• A polygon with four sides and four
angles.
Example:
12.3
pentagon
• A polygon with five sides and five
angles.
Examples:
12.3
hexagon
• A polygon with six sides.
Examples:
12.3
octagon
• A polygon with eight sides and eight
angles.
Examples :
12.3
Decagon
• A polygon with ten sides and ten angles.
Example:
12.3
intersecting lines
• lines that cross
Example:
12.4
perpendicular lines
• Lines that intersect to form right
angles.
Example:
12.4
parallel lines
• Lines that never cross; lines that are
always the same distance apart.
Example:
12.4
parallelogram
• A quadrilateral whose opposite sides
are parallel and have the same length.
Example :
trapezoid
• A quadrilateral with exactly one pair
of parallel sides and four angles.
Example:
rectangle
A quadrilateral with 2 pairs of parallel
sides, 2 pairs of equal sides, and 4 right
angles.
Example:
12.5
square
A quadrilateral with 2 pairs of parallel
sides, 4 equal sides, and 4 right angles.
Example:
12.5
rhombus
• A quadrilateral with 2 pairs of parallel
sides and 4 equal sides and four
angles.
Example:
12.5
equilateral triangle
• A triangle that has three equal sides
and three equal angles.
• Examples:
isosceles triangle
• A triangle that has two equal sides.
Example:
scalene triangle
• A triangle in which no sides are equal
Example:
right triangle
• A triangle with one right angle
Example:
obtuse triangle
• A triangle that has 1 obtuse angle.
Example:
acute triangle
• A triangle that has three acute angles.
Example:
Venn Diagram
A diagram that shows relationships among
sets of things.
12.8
diagonal
• A line segment that connects two
vertices of a polygon that are not next
to each other
Example:
congruent
• Figures that have the same size and
shape.
Example:
symmetry
• A figure has symmetry if it can be folded
along a line so that the two parts match
exactly; one half of the figure looks like the
mirror image of the other half.
Example:
line of symmetry
line of symmetry
• An imaginary line on a figure that
when the figure is folded on this line,
the two parts match exactly.
Example :