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Calculating Area of Composite Shapes
Nov 24, 2024
Finding the Area of Composite Shapes
Introduction
Topic
: Finding areas of complex shapes by decomposing them into simpler shapes.
Challenge
: Strange shapes don't have predefined area formulas like rectangles or triangles.
Solution
: Break complex shapes into simple shapes with known formulas.
Simple Shapes and Their Formulas
Rectangles
: Area = Length x Width
Parallelograms
: Formula not specified in transcript
Triangles
: Area = 1/2 x Base x Height
Trapeziums
: Area = (a + b)/2 x Height
Approach to Composite Shapes
Composite Shapes
: Made of two or more simple shapes.
Strategy
: Split the shape into rectangles, triangles, and/or trapeziums and calculate each area separately.
Example 1: Composite Shape Breakdown
Shape Description
: Top part is a triangle, bottom part is a rectangle.
Steps
:
Rectangle Area
:
Formula Used
: Length x Width
Calculation
: 5cm x 4cm = 20cm²
Triangle Area
:
Formula Used
: 1/2 x Base x Height
Given
: Base = 5cm, Height needs calculation
Height Calculation
: Overall height = 7cm, Rectangle height = 4cm
Height of Triangle
: 7cm - 4cm = 3cm
Area Calculation
: 1/2 x 5cm x 3cm = 7.5cm²
Total Area
: 20cm² + 7.5cm² = 27.5cm²
Example 2: Composite Shape with Trapezium
Shape Description
: Bottom is a rectangle, top is a trapezium.
Steps
:
Rectangle Area
:
Formula Used
: Length x Width
Calculation
: 15cm x 12cm = 180cm²
Trapezium Area
:
Formula Used
: (a + b)/2 x Height
Given
: Top length (a) = 4cm, Bottom length (b) = 6cm, Height = 5cm
Average Length Calculation
: (4cm + 6cm)/2 = 5cm
Area Calculation
: 5cm x 5cm = 25cm²
Total Area
: 180cm² + 25cm² = 205cm²
Conclusion
Composite shapes can be broken down into simple shapes with known area formulas.
Calculation involves finding and summing the areas of each simple shape.
Additional Resources
Website
: Visit our live past paper website for more resources.
Access
: Click the button in the top right corner of this screen.
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