Classification and Properties of 2D Shapes
2D shapes are flat shapes that have only two dimensions: length and width. We see these shapes everywhere around us - in books, signs, toys, and even food!
Basic 2D Shapes
Let's learn about some common 2D shapes:
- Circle: A round shape where all points on the edge are the same distance from the center.
- Triangle: A shape with 3 sides and 3 vertices (corners).
- Rectangle: A shape with 4 sides and 4 vertices. Opposite sides are equal and all angles are right angles (90°).
- Square: A special rectangle where all 4 sides are equal.
- Pentagon: A shape with 5 sides and 5 vertices.
- Hexagon: A shape with 6 sides and 6 vertices.
Important Parts of 2D Shapes
When we talk about 2D shapes, we use special words:
- Sides: The lines that make up a shape. For example, a triangle has 3 sides.
- Vertices (or corners): Where two sides meet. A square has 4 vertices.
- Angles: The space between two sides that meet. A right angle looks like the corner of a piece of paper (90°).
Types of Triangles
Triangles can be sorted by their sides:
- Equilateral triangle: All 3 sides are equal in length.
- Isosceles triangle: 2 sides are equal in length.
- Scalene triangle: No sides are equal in length.
Triangles can also be sorted by their angles:
- Right triangle: Has one right angle (90°).
- Acute triangle: All angles are less than 90°.
- Obtuse triangle: Has one angle more than 90°.