Area of Plane Shapes
Learn more about Area, or try the Area Calculator.
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Triangle Area = ½ × b × h b = base h = vertical height |
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Square Area = a2 a = length of side |
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Rectangle Area = w × h w = width h = height |
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Parallelogram Area = b × h b = base h = vertical height |
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Trapezoid (US) Trapezium (UK) Area = ½(a+b) × h h = vertical height |
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Circle Area = π × r2 Circumference = 2 × π × r r = radius |
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Ellipse Area = πab |
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Sector Area = ½ × r2 × θ r = radius θ = angle in radians |
| Note: h is at right angles to b: |  |
Example: What is the area of this rectangle?
The formula is:
Area = w × h
w = width
h = height
We know w = 5 and h = 3, so:
Area = 5 × 3 = 15
Example: What is the area of this circle?
Radius = r = 3
| Area | = π × r2 | |
| = π × 32 | ||
| = π × (3 × 3) | ||
| = 3.14159... × 9 | ||
| = 28.27 (to 2 decimal places) |
Example: What is the area of this triangle?
Height = h = 12
Base = b = 20
Area = ½ × b × h = ½ × 20 × 12 = 120
A harder example:
Example: Sam cuts grass at $0.10 per square meter
How much does Sam earn cutting this area:
Let's break the area into two parts:
Part A is a square:
Area of A = a2 = 20m × 20m = 400m2
Part B is a triangle. Viewed sideways it has a base of 20m and a height of 14m.
Area of B = ½b × h = ½ × 20m × 14m = 140m2
So the total area is:
Area = Area of A + Area of B = 400m2 + 140m2 = 540m2
Sam earns $0.10 per square meter
Sam earns = $0.10 × 540m2 = $54