Area, Perimeter & Volume
Calculate area of triangles and volume of rectangular prisms
Perimeter
Perimeter is the total distance around a 2D shape. Add all the side lengths.
Rectangle: P = 2(l + w)
Square: P = 4s
Triangle: P = a + b + c
Area
Area is the amount of surface a 2D shape covers, measured in square units (cm², m²).
Rectangle: A = length × width
Square: A = side × side = s²
Triangle: A = (1/2) × base × height
Example
Worked Examples — Area and Perimeter
Rectangle: l = 12 cm, w = 5 cm
P = 2(12 + 5) = 2 × 17 = 34 cm
A = 12 × 5 = 60 cm²
Triangle: base = 8 cm, height = 6 cm, sides = 8, 6, 10 cm
P = 8 + 6 + 10 = 24 cm
A = (1/2) × 8 × 6 = 24 cm²
Volume
Volume is the amount of space a 3D object takes up, measured in cubic units (cm³, m³).
Rectangular prism: V = length × width × height
Cube: V = s³
Example
Volume Example
A box has length 10 cm, width 4 cm, height 3 cm.
V = 10 × 4 × 3 = 120 cm³
A cube has side 5 cm.
V = 5³ = 5 × 5 × 5 = 125 cm³
Key Vocabulary
PerimeterThe total distance around a shape
AreaThe amount of surface a shape covers (in square units)
VolumeThe amount of space inside a 3D object (in cubic units)
Square unitsUnits like cm² used to measure area
Cubic unitsUnits like cm³ used to measure volume
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