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Math Vocabulary: Geometry Terms
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Gravity
Geometry terms for 4th graders in Ohio
Terms in this set (38)
vertex (vertices)
the point where 2 lines, line segments, or rays intersect (vertices is more than 1)
line
straight; has arrows on both ends to show that the line continues forever
line segment
a part of a line; has a beginning point and an ending point
ray
part of a line; has a beginning OR an ending point, the other side continues forever (has an arrow)
angle
formed when 2 lines, line segments, or rays share a vertex
polygons
2-D shapes that have straight sides, are closed, and the sides do not intersect or cross
acute triangle
a triangle with 3 acute angles
triangle
a 3 sided polygon (also has 3 angles)
equilateral triangle
a triangle with 3 equal sides (all sides are the same length)
isosceles triangle
a triangle with 2 sides the same length
scalene triangle
a triangle where all 3 sides are different lengths
right triangle
a triangle with 1 right (90 degrees) angle
obtuse triangle
a triangle with 1 obtuse (more than 90 degrees) angle
quadrangle
a polygon with 4 angles (also known as a quadrilateral)
quadrilateral
a polygon with 4 sides (also known as a quadrangle)
square
a quadrilateral (4 sided polygon) with 4 right angles and all 4 sides are the same length
rectangle
a quadrilateral (4 sided polygon) with 4 right angles and opposite sides are parallel and the same length (top = bottom and left = right)
kite
a quadrilateral (4 sided polygon) where no sides are parallel
rhombus
a quadrilateral (4 sided polygon) where all 4 sides are the same length, but does not have to have 4 right angles
pentagon
a 5 sided polygon
hexagon
a 6 sided polygon
regular pentagon
a 5 sided polygon where all 5 sides are the same length
regular hexagon
a 6 sided polygon where all 6 sides are the same length
octagon
an 8 sided polygon
perimeter
the distance around a polygon or shape; the outside border(measure all of the sides and add the distances together)
area
the space an object takes up or occupies (inside area)
Area of a Rectangle
Area = length x width or
Area = base x height
Area of a Parallelogram
Area = base x height
** The height must be perpendicular to the base
Area of a Triangle
Area = 1/2 (base x height) or Area = (base x height)/2
** The height must be perpendicular to the base
parallel
lines or line segments that are always the same distance apart; they will never touch (like railroad tracks!)
perpendicular
lines or line segments that intersect to form right angles (90 degree angles)
intersecting
lines or line segments that intersect or cross, do not necessarily form right angles
actue angle
an angle that measures less than 90 degrees ("a cute" little . . . )
right angle
an angle that measures exactly 90 degrees (a square corner)
obtuse angle
an angle that measures more than 90 degrees
straight angle
an angle that measures exactly 180 degrees (straight line)
convex
a polygon where all of the vertices are outside of the shape; A polygon in which all vertices appear to be pushed outward.
concave (nonconvex)
a polygon where one or more vertices is on the inside of the polygon; A polygon in which at least one vertex appears to be pushed inward.
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