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Quick Math Homework Help
  • Two dimensional shapes can have straight lines or curved lines. 
  • A 2D shape has no thickness, and only two dimensions such as height and width.
  • They are also known as 2 dimensional shapes or 2D shapes.
  • Many two dimensional shapes are also classified as a plane shape.  
  • A plane shape is a closed, two-dimensional shape. They vary according to the numbers of sides or vertices.
  • A vertex is where two sides meet. If you draw a line from two vertices that are not next to each other, this line would be called a diagonal. 
Ellipse A closed loop formed by a curved line. The distance from A to C plus B to C will be constant regardless of the location of C on the curved line.
A
C
B
Common Core Standard  5.G.B.3     5.G.B.4
Keywords: Two dimensional figures,attributes, classify
Related sites 2d Shapes
side diagonal and vertex of a plane shapeplane shapes


A triangle has  three sides and three vertices. Here is a list of some common triangles.
Polygons are classified by the number of sides. The number of sides and vertices are equal in polygons. 

Classifying polygons by the number of sides

3 sides =triangle

4 sides =quadrilateral

5 sides= pentagon

6 sides =hexagon

7 sides =septagon

8 sides =octagon

9 sides =nonagon

10 sides =decagon

12 sides =dodecagon

n sides =n-gon

Polygons/2 Dimensional Shapes

equilateral triangle/example 2 dimensional shape
2d shape / scalene triangle
equilateral triangle/2d shape
isosceles triangle/two dimensional shape example
rectangle
square/plane shape
circle/2d plane shape
parallelogram
quadrilaterals
rhombus/2 dimensional shape example
trapezoid
Click on the  shape for more information
Click on the shape for more information
Click on the shape for more information
Scalene triangles have three different side lengths and three different angle measures
Isosceles triangles have at least two equal sides and two equal angle measures
Equilateral triangles have equal sides and angles.
rectangle is a shape with four sides and four vertices
square is a rectangle in which all four sides are equal length and create four ninety degree angles
circle is a round shape that has no sides or corners
parallelogram has four sides, four vertices, and two parallel sides
quadrilateral has four sides, four vertices, and two diagonals. There are many types of quadrilaterals. Check here for a chart of the quadrilateral family.


rhombus has four sides, four vertices, and four equal sides.
trapezoid has four sides, four vertices, and exactly one pair of parallel sides.
Click on the 2 dimensional  shape for more information
Click on the  shape for more information

2 Dimensional Polygon Shapes

What is a 2D shape? A shape that has only two dimensions such as width and height, but has no thickness is considered a two dimensional shape. Polygons are 2D shapes.
25 Names of 2D Shapes

Circle: Round Shape  
Right Triangle: 3 sides 1 90 degree angle  
Rhombus: 4 sides opposite angles equal 
Trapezoid: 4 sides opposite are parallel 
Pentagon: 5 sides  
Hexagon: 6 sides   
Octagon: 7 sides  
Nonagon: 9 sides  
Decagon: 10 sides     
Star:  a polygon formed by extending the sides of a pentagon        
Diamond: also called a rhombus
Crescent: (looks like a sliver of the moon)  
Semi-circle: half of acircle
All quadrilaterals: 4 sided polygons     
Arrows:  also called a dart
Convex polygon:  no internal angles 180 degrees or greater   
Concave polygon: at least one internal angle greater than 180 degrees
Dart: a concave dart    
Kite:  a 4 sided polygon   
Triangle: 3 sided 2d shape    
Disc:  a circular shape 
Circumcircle: the middle of the circle that touches the three vertices of a triangle 
Indalo:  a prehistoric magical symbol 
Lune: two overlapping circles  
Oval:  think of an egg

This list is just the tip of the iceberg for two dimensional shapes.