point
an exact position often marked as a dot
line
a straight path of points that is endless in two directions
line segment
a part of a line with two endpoints
intersecting lines
lines that cross at one point
parallel lines
lines that never cross
ray
a part of a line that has one endpoint and continues endlessly in one direction
angle
a figure formed by two rays that have the same endpoint.
vertex plural: vertices
1. the point where two rays met to form an angle.
2. the points where the sides of a polygon meet
3. the points where 3 or more edges meet in a
solid figure that does not roll.
4. the pointed part of a cone
right angle
an angle that forms one square corner or 90 degree angle
acute angle
an angle that's open end measures less than a right angle
obtuse angle
an angle that's open measures more than a right angle
perpendicular
two lines, line segments or rays that form right angles
polygon
a closed figure made up of line segments
side
a line segment forming part of a polygon
triangle
a polygon with 3 sides and 3 vertices
quadrilateral
a polygon with 4 sides and 4 vertices
pentagon
a polygon with 5 sides and 5 vertices
hexagon
a polygon with 6 sides and 6 vertices
octagon
a polygon with 8 sides and 8 vertices
decagon
a polygon with 10 sides and 10 vertices
equilateral triangle
a triangle with all sides the same length
isosceles triangle
a triangle with at least two sides the same length
scalene triangle
a triangle with no sides the same length
right triangle
a triangle with one right angle
acute triangle
a triangle with 3 acute angles
obtuse triangle
a triangle with one obtuse angle
trapezoid
a quadrilateral with only one pair of parallel sides
parallelogram
a quadrilateral in which opposite sides are parallel
rectangle
a quadrilateral with four right angles. It is a special parallelogram
rhombus
a quadrilateral with opposite sides parallel and all sides the same length. Opposite angles are obtuse and the other opposite angles are acute. It is a special parallelogram
square
a quadrilateral with 4 right angles and all sides the same length. it is a special parallelogram and a combination of a rectangle and rhombus
diagonal
a line segment other that a side that connects two vertices of a polygon