# Plane shapes

Plane Shapes

What is a plane shape? A plane shape is a closed, two-dimensional shape. Plane shapes vary according to the numbers of sides or vertices. A vertex is where two sides meet. If a draw a line from two vertices that are not next to each other this line would be called a diagonal. There are many plane shapes and here is a list of several common plane shapes.

A triangle is a plane shape with three sides and three vertices. Here is a list of some common triangles.

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.

A rectangle is a shape with four sides and four vertices

A square is a rectangle in which all four sides are of equal length and create four ninety degree angles.

A circle is a round shape that has no sides or corners.

A parallelogram has four sides, four vertices, and two parallel sides.

A quadrilateral is a plane shape with four sides, four vertices, and two diagonals. There are many types of quadrilaterals and check here for a chart of the quadrilateral family.

A rhombus has four sides, four vertices, and four equal sides.

A trapezoid has four sides, four vertices, and exactly one pair of parallel sides.

Polygons are plane shapes classified by the number of sides. The number of sides and vertices are equal in polygons.

Classifying polygons by the number of sides

3 triangle

5 pentagon

6 hexagon

7 septagon

8 octagon

9 nonagon

10 decagon

12 dodecagon

n  n-gon