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📐 Mathematics  ·  Circles & Mensuration  ·  JEE

The area of a regular hexagon with side a:

Answer: 3√3 a²/2.

  • A 3√3 a²/2
  • B 6a²
  • C 3a²
  • D 2√3 a²

Correct answer: A. 3√3 a²/2

Explanation: A regular hexagon splits into 6 equilateral triangles, each with side a. Area of one equilateral triangle=√3a²/4. Total=6×(√3a²/4)=3√3a²/2. E.g. a=2 gives area=6√3 ≈10.39. Ans: 3√3a²/2.

Cylinder, Cone, SphereV=πr²hCSA=2πrhV=⅓πr²hCSA=πrlV=4/3πr³SA=4πr²

Three standard 3D solids and their key formulas: a cylinder's volume scales with the full height, a cone's volume is exactly one-third of the cylinder with the same base and height, and a sphere's volume and surface area both follow distinct r-based formulas worth memorising separately.

Concept context

Perimeters, areas, and volumes of 2D and 3D shapes

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