Two-dimensional Shapes have dimensions in only 2 directions - a width and a length.
Plane Shapes - Same as 2-dimensional shapes; The word plane means flat because these shapes are on flat surfaces
Polygons - 2D shapes with straight sides e.g. triangle, rectangle
Regular Polygons - Polygons with all sides of equal length e.g. equilateral triangle and square
NUMBER OF SIDES | NAME OF POLYGON |
3 | triangle |
4 | quadrilateral |
5 | pentagon |
6 | hexagon |
7 | heptagon |
8 | octagon |
9 | nonagon |
10 | decagon |
11 | undecagon un- = 1 deca- = 10 |
12 | dodecagon do- = 2 deca- = 10 |
Most names for 2D shapes and 3D solids come from the Greek language.
Many 2D shapes have names ending in -gon. Many 3D solids have names ending in -hedron.
Hept- is Greek for "seven". Sept- is Latin for "seven".
DIAGRAM | NAME OF TRIANGLE | PROPERTIES |
Right-angled triangle | Has one angle of 90° Longest side is called the hypotenuse | |
Equilateral triangle | 3 sides are equal 3 angles are equal Each angle is 60° | |
Isosceles triangle | 2 sides are equal 2 angles are equal | |
Scalene triangle | No sides are equal No angles are equal |
PARALLELOGRAM
|
RHOMBUS
|
RECTANGLE
|
SQUARE
|
TRAPEZOID
|
KITE
|
Q1. I have 3 sides of equal length.
Q2. I have 4 equal sides, my diagonals bisect each other and the angles, and none of my angles are right angles.
Q3. I have 2 pairs of equal sides, my diagonals are not equal, my diagonals meet each other at right angles, and one pair of my opposite angles is equal.
Answers
A1. equilateral triangle
A2. rhombus
A3. kite