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📐 Mathematics  ·  Circles & Mensuration  ·  JEE

A chord of the circle x² + y² = 25 subtends a right angle at the centre. Its length is:

Answer: 5√2.

  • A 5
  • B 5√2
  • C 10
  • D 5√3

Correct answer: B. 5√2

Explanation: The chord is the hypotenuse of a right isosceles triangle with legs 5, so its length is 5√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

Read the full Circles & Mensuration notes →