Class 8 Maths - HARYANA
Area
The chapter 'Area' in Class 8 Mathematics builds upon basic geometric shapes to help students calculate the surface area of closed 2D and 3D figures. Students learn to find the area of polygons like trapeziums, general quadrilaterals, and regular hexagons by splitting them into simpler triangles and rectangles. Additionally, the chapter covers the surface area of solid shapes such as cubes, cuboids, and cylinders. This chapter is vital for the Haryana (BSEH) board exams as it tests both conceptual understanding and calculation accuracy, frequently featuring in both short-answer and long-answer problem sets.
Start Learning FreeKey Concepts
Area of a Trapezium
The area of a trapezium is calculated as half the product of the sum of its parallel sides and the perpendicular distance between them.
Area of a General Quadrilateral
To find the area of any general quadrilateral, it is divided into two triangles by drawing a diagonal, and the sum of their areas is calculated.
Surface Area of a Cube
The total surface area of a cube is the sum of the areas of its 6 identical square faces, given by six times the square of its side length.
Surface Area of a Cuboid
The total surface area of a cuboid is the sum of the areas of its 3 pairs of rectangular faces, calculated as two times (length times breadth plus breadth times height plus height times length).
Surface Area of a Cylinder
The total surface area of a right circular cylinder includes the curved surface area plus the areas of the two circular bases at the top and bottom.
Important Formulas
Board Exam Info
In the Haryana (BSEH) Class 8 Mathematics board exams, the chapter on Area typically carries around 6 to 8 marks. Questions usually include 1-mark objective questions, 2-mark direct formula application sums, and 4-mark word problems involving combined shapes or calculating painting/cost expenses based on surface area.
Frequently Asked Questions
What is the difference between curved surface area and total surface area?
Curved surface area (CSA) only includes the outer walls or curved part of a 3D object like a cylinder, leaving out the top and bottom bases. Total surface area (TSA) includes the CSA plus the areas of the top and bottom bases.
How do I find the area of a polygon that is not a standard shape?
You can split the irregular polygon into standard shapes like triangles, rectangles, or trapeziums using diagonals or perpendicular lines, find the area of each smaller part separately, and then add them all together.
Why do we use 'pi' (π) in cylinder formulas?
Pi (π) is a mathematical constant used whenever circular shapes are involved. Since a cylinder has circular bases, π is needed to calculate their perimeter (circumference) and area.
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