Q1
What is perimeter?
AThe sum of all boundary lengths
BThe enclosed space
CThe height of a shape
DThe colour of a shape
ICSEClass 9 (ICSE)MathematicsCh 20 · Topic 1
Area and Perimeter of Plane Figures
Calculating the area and perimeter of plane figures like triangles, quadrilaterals, and circles uses specific formulas based on their dimens
Core concept
The perimeter of any figure is the sum of all its boundary lengths, while area measures the space enclosed within the figure.
How it works
For a triangle, area = (1/2) × base × height, and for a circle, area = π × radius², with circumference = 2 × π × radius.
Why it matters
For combined or composite figures, we can calculate area by breaking the figure into simpler shapes and adding their areas.
Key detail
Mastering these formulas is essential for solving real-world problems involving land measurement, construction, and design.
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Quick notes
• Perimeter is the sum of boundary lengths.
• Area measures enclosed space.
• Triangle area = (1/2) × base × height.
• Circle area = π × radius².
• Circle circumference = 2 × π × radius.
• Composite figures break into simpler shapes.
• We add areas of simpler shapes together.
• These formulas apply to real-world measurement problems.