Twodimensional Shapes have dimensions in only 2 directions  a width and a length.
Plane Shapes  Same as 2dimensional 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 
Rightangled 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