Shapes
You need to know the properties of the different types of triangle and square. Circles always have a radius, a diameter, and a circumference. You also need to know about other polygons such as hexagons and pentagons.
The perimeter is the length of the sides of a shape, and the area is the surface area that it covers. You need to know how to work out how many lines of symmetry a 2D shape has.
Every object that you see has a particular shape. A shape is the form of an object or its external boundary.
In the following sections we shall explore the different types of shapes.
Triangles
A geometrical object with three sides (i.e. three edges and three vertices) is called a triangle.
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Here are the different types of triangles:
| Equilateral Triangle | Isosceles Triangle | Scalene Triangle | Right Angled Triangle |
|---|---|---|---|
| 3 equal sides | 2 equal sides | No equal sides | |
| 3 equal angles of 60 degree each | 2 equal angles | No equal angles | One of the angles is 90 degree. |
| [IMAGE] | [IMAGE] | [IMAGE] | [IMAGE] |
Quadrilateral
A geometrical object with four sides (i.e. four edges and four vertices) is called a quadrilateral. Quad means four and lateral means side.
Here are different types of quadrilaterals:
| Square | Rectangle | Rhombus | Parallelogram |
|---|---|---|---|
| 4 equal sides | 2 pairs of equal sides | 4 equal sides. Opposite sides are parallel. |
2 pairs of equal sides. Opposite sides are parallel. |
| 4 right angles | 4 right angles | Opposite angles are equal | Opposite angles are equal |
| [IMAGE] | [IMAGE] | [IMAGE] | [IMAGE] |
Different types of quadrilaterals
| Trapezium | Kite | |
|---|---|---|
| 1 of the pairs of side is equal (with different length) | 2 pairs of equal sides adjacent to each other. No parallel sides. |
|
| [IMAGE] | [IMAGE] | [IMAGE] |
Circle
A circle is the set of all points in a plane that are at a given distance from a given point, the centre. Every circle has circumference and diameter (radius). Let us understand what they mean:
[IMAGE]
Polygons
Polygons are shapes with finite straight lines (edges) that join together to form a closed figure.
Here are some regular polygons:
| Regular Pentagon | Regular Hexagon | Regular Heptagon | Regular Octagon |
|---|---|---|---|
| 5 sides | 6 sides | 7 sides | 8 sides |
| [IMAGE] | [IMAGE] | [IMAGE] | [IMAGE] |
Perimeter and Area
[IMAGE]
In the above figure, the perimeter is given by;
Area is the total amount of surface a 2D geometrical object covers. In simple terms it is the product of length and width of an object.
[IMAGE]
In the above figure, the area is given by;
