Mensuration — Formula Sheet
Tamil Nadu Board · Class 9 · Mathematics
6 formulas from Mensuration (Tamil Nadu Board Class 9 Mathematics) on one page, grouped by topic. Includes Semi-perimeter (s) is half and For Cuboid.
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Formulas and Key Relations
1 - 7.2: Heron's Formula and Triangle Areas
Semi-perimeter (s) is half the perimeter
s = (a + b + c)/2
Area = √[s(s-a)(s-b)(s-c)] square units
5: Volume of Cuboids and Cubes
Volume = Base Area × Height
For Cuboid
V = l × b × h (length × breadth × height)
Key relations
For a triangle with sides a, b, and c, the semi-perimeter s = (a+b+c)/2.
The formula is TSA = 2(lb + bh + lh) square units.
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