Area and Perimeter of Plane Figures — Chapter Summary
ICSE · Class 9 · Mathematics
Summary of Area and Perimeter of Plane Figures for ICSE Class 9 Mathematics. Part of the ICSE Class 9 Mathematics syllabus.
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Overview
Perimeter is the length of the boundary of a plane figure, and area is the measure of the surface enclosed by that boundary. Perimeter is measured in units of length such as cm or m, while area is measured in square units such as cm² or m². The chapter builds the skill of finding area and perimeter
Key Concepts
Perimeter is the length of
Perimeter is the length of the boundary of a plane figure. Its unit is the same as the unit of length, such as cm or m.
Area is the measure of
Area is the measure of the surface enclosed by the boundary of a plane figure. It is measured in square units.
Area of triangle = 1/2 ×
Area of triangle = 1/2 × base × corresponding height (altitude). Any side of a triangle can be taken as the base, and the matching perpendicular is th
Area = √(s(s
Area = √(s(s-a)(s-b)(s-c)), where s = (a+b+c)/2. It is used when all three sides are known.
All sides are equal
All sides are equal. Perimeter = 3a and Area = (√3/4)a², where a is the side.
Learning Objectives
- Define perimeter and area correctly and distinguish between their units.
- Use the area formula of a triangle with base and corresponding height.
- Apply Heron's formula when the three sides of a triangle are known.
- Solve area problems for equilateral, isosceles, and right-angled triangles.
- Find area and perimeter of rectangles, squares, parallelograms, rhombuses, trapeziums, and circles.
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Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.
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