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