About elementary shapes
"Understanding Elementary Shapes" teaches you:
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How to classify and measure lines and angles
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To identify 2D and 3D shapes around you
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To use a ruler and protractor for accurate geometry
This chapter builds your visual and spatial skills for more advanced geometry in higher classes.
- All Level
- Last updated 15-May-2025
- english
Course description
What You’ll Learn
This chapter helps you:
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Identify different types of lines, angles, and shapes
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Classify triangles and quadrilaterals
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Measure line segments and angles
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Understand 2D and 3D shapes
key Concepts
1. Measuring Line Segments
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Use a ruler or scale to measure the length of a line segment.
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Measurement is done in centimetres (cm) and millimetres (mm).
Example:
Length of AB = 6.4 cm
2. Types of Lines
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Straight line
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Curved line
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Horizontal line (left to right)
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Vertical line (top to bottom)
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Slanting line (diagonal)
3. Angles and Their Types
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An angle is formed when two rays meet at a common point (vertex).
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Measured in degrees (°) using a protractor.
Types of Angles
| Angle Type | Description | Example Measure |
|---|---|---|
| Acute Angle | Less than 90° | 30°, 45° |
| Right Angle | Exactly 90° | 90° |
| Obtuse Angle | More than 90° and less than 180° | 120°, 145° |
| Straight Angle | Exactly 180° | 180° |
| Reflex Angle | Greater than 180° and less than 360° | 220°, 300° |
| Complete Angle | Exactly 360° | 360° |
4. Measuring Angles
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Use a protractor to measure angles.
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Align one arm of the angle with the base line of the protractor.
5. Triangles and Their Types
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A triangle has 3 sides and 3 angles.
Types of Triangles (based on angles):
| Type | Description |
|---|---|
| Acute-angled | All angles are acute |
| Right-angled | One angle is 90° |
| Obtuse-angled | One angle is obtuse |
Types of Triangles (based on sides):
| Type | Description |
|---|---|
| Scalene | All sides are different |
| Isosceles | Two sides are equal |
| Equilateral | All sides are equal |
6. Quadrilaterals
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A polygon with 4 sides and 4 angles.
Examples of Quadrilaterals:
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Square: All sides and angles are equal
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Rectangle: Opposite sides are equal, all angles are 90°
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Rhombus: All sides are equal, opposite angles equal
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Parallelogram: Opposite sides are parallel and equal
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Trapezium: One pair of opposite sides is parallel
7. Polygons
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Closed figures with 3 or more sides.
| Sides | Name |
|---|---|
| 3 | Triangle |
| 4 | Quadrilateral |
| 5 | Pentagon |
| 6 | Hexagon |
8. 3D Shapes (Solid Figures)
You also learn to recognize and name solid shapes like:
| Shape | Faces | Edges | Vertices |
|---|---|---|---|
| Cube | 6 | 12 | 8 |
| Cuboid | 6 | 12 | 8 |
| Cylinder | 3 | 2 | 0 |
| Cone | 2 | 1 | 1 |
| Sphere | 1 | 0 | 0 |
This course includes
- Lectures 10
- Duration 4h 50m
- Skills All Level
- Language english
- Certificate yes
Sample
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