44 terms

# Geometry

Geometry vocabulary

#### Terms in this set (...)

plane
a flat surface that goes on and on in each direction
point
a particular place on a plane - named with a letter
end point
a point at the start of a ray or at either end of a line segment
line
a straight path that goes on without end in opposite directions. name a line segment by naming only 2 points on that line
line segment
a place on a straight line- name a line segment by naming the 2 endpoints
ray
has an endpoint and goes on forever in one direction. Must name the endpoint first and then name any other point on the ray
intersecting lines
lines that cross, where they cross is called the point of intersecting
parallel lines
lines that are always the same distance apart. They will never intersect.
perpendicular lines
lines that intersect to form right angles
angle
two rays that share a common endpoint
vertex
the endpoint that 2 rays have in common.
The vertex is always named in the middle of an angle
right angle
measures 90 degrees - a corner
acute angle
measures less than 90 degrees, less than a right angle
obtuse angle
measures greater than 90 degrees, more than a right angle
polygon
a closed figure (plane) made up of line segments
non polygon
a closed figure made up of any shape with curves
triangle
a plane with three sides
acute triangle
3 acute angles - all angles are less than 90 degrees
obtuse triangle
1 obtuse angle - more than 90 degrees
right triangle
1 right angle - a 90 degree angle
equilateral triangle
all 3 sides are equal in length
isosceles triangle
2 sides are equal in length and 2 angles are equal
scalene triangle
all 3 sides are different in length all angles are different measurements
a plane figure with 4 sides
parallelogram
a quadrilateral with 2 pairs of parallel sides
square
all sides are the same length and has 4 right angles
rectangle
opposite sides are parallel, equal in length and has 4 right angles
trapezoid
quadrilateral with only 1 pair of parallel lines
rhombus
quadrilateral with 2 pairs of parallel sides, all sides are the same length
similar
2 figures that are the same shape but not the same size
congruent
2 figures that are the same shape and the same size
reflection
flip- over a line
translation
slide- a figure across a line
rotation
turn - a figure around a point
symmetry
a figure that can be folded on a line to form 2 congruent halves
chord
a line that connects 2 points on a circle
diameter
distance from one end of a circle to the other
line segment from the center of the circle to every point on a circle
circumferences
the distance around the outside of a circle
perimeter
the distance around a closed figure (units)
area
the number of square units needed to cover a figure ( square units)
volume
the number of cubic units to cover a figure ( cubic units)
face
a flat surface of a solid
edges
a line segment where 2 faces of a solid figure meet

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