Overview
This lecture explains how to calculate the surface area of a cuboid by finding and adding the areas of all its rectangular faces.
Surface Area of a Cuboid
- A cuboid has six rectangular faces: front, back, left, right, top, and bottom.
- To find the surface area, calculate the area of each face and add them together.
- Opposite faces are equal in area (e.g., front = back, top = bottom).
Example 1: Surface Area Calculation
- Dimensions: Height = 3 cm, Width = 12 cm, Depth = 10 cm.
- Front and back: 3 × 12 = 36 cm² each.
- Left and right: 3 × 10 = 30 cm² each.
- Top and bottom: 12 × 10 = 120 cm² each.
- Add all face areas: 36 + 36 + 30 + 30 + 120 + 120 = 372 cm².
- Surface area is always measured in square units (cm²).
Example 2: Another Cuboid Calculation
- Dimensions: Height = 2 cm, Width = 3 cm, Depth = 3 cm.
- Front and back: 2 × 3 = 6 cm² each.
- Right and left: 2 × 3 = 6 cm² each.
- Top and bottom: 3 × 3 = 9 cm² each.
- Add all face areas: 6 + 6 + 6 + 6 + 9 + 9 = 42 cm².
Key Terms & Definitions
- Cuboid — A 3D shape with six rectangular faces.
- Surface Area — The total area covering the outside of a 3D object, measured in square units.
Action Items / Next Steps
- Practice calculating the surface area of different cuboids using given dimensions.
- Check that all six face areas are included in calculations.