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
Types of Polygons
|NUMBER OF SIDES||NAME OF POLYGON|
un- = 1
deca- = 10
do- = 2
deca- = 10
Did You Know That...?
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".
Types of Triangles
|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
Types of Quadrilaterals
Questions - What am I?
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.
A1. equilateral triangle