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• 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 2D shapes.
• Many two dimensional shapes are also classified as polygons.
• A plane shape which is a closed, two-dimensional shape is a 2D shape. They vary according to the numbers of sides or vertices.
• Many 2D shapes are named according to their number of 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. ( See below )
• When placed on a sheet of paper, 2D shapes lay flat.
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
Geometric shapes: 2-dimensional-Helping with Math

Geometric Shapes and Names 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

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

# 2 Dimensional Shapes

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 and is not a polygon, but is a 2D shape.
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.

## 2 Dimensional Polygon Shapes

What is a 2 dimensional 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