trapezium
A quadrilateral (4-sided shape) with one pair of parallel sides
quadrilaterals
4 sided polygon
parallelogram
A quadrilateral with two pairs of parallel sides
rhombus
A parallelogram with four equal sides
rectangle
A parallelogram with four right angles
square
4 equal sides. 90 degree angles.
isosceles
A triangle that has 2 equal sides.
equilateral
A triangle that has all three sides the same length.
scalene
A triangle with no equal sides
triangle
a three-sided polygon
right angled triangle
A triangle with a right angle
protractor
A tool used to measure angles
radius
A straight line from the center to the circumference of a circle or sphere.
diameter
A straight line passing from side to side through the center of a circle or sphere.
circumference
The distance around a circle
arc
the shape of part of a circle
sector
The part of a circle that looks like a piece of pie. A sector is bounded by 2 radii and an arc of the circle.
parallel
If two or more lines, streets, etc. are parallel, the distance between them is the same all along their length
perpendicular
At an angle of 90? to a given line, plane, or surface.
vertical
standing or pointing straight up or at an angle of 90� to a horizontal surface or line
horizontal
Going straight across from side to side
acute angle
An angle less than 90 degrees
right angle
90 degree angle
obtuse angle
An angle between 90 and 180 degrees
straight angle
An angle of 180 degrees
reflex angle
Between 180 and 360 degrees
pentagon
5 sided polygon
hexagon
6 sided polygon
heptagon
A polygon with 7 sides.
octagon
8 sided polygon
nonagon
A polygon with 9 sides
decagon
10 sided polygon
hendecagon
11 sided polygon
dodecagon
12 sided polygon