Multiple choice

A chord of a circle is 12 cm in length and its distance from the centre is 7 cm. Find the length of the chord of the same circle which is at a distance of 6 cm from the centre.

  1. 14 cm

  2. 18 cm

  3. 24 cm

  4. 30 cm

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A Correct answer
Explanation

Radius squared = (12/2)^2 + 7^2 = 36 + 49 = 85. For the second chord, (L/2)^2 + 6^2 = 85. (L/2)^2 = 85 - 36 = 49. L/2 = 7, so L = 14.

AI explanation

Using the perpendicular bisector property of a chord, the radius squared equals 7 squared plus 6 squared, yielding 85. For the second chord at a distance of 6 cm, half its length squared equals the radius squared minus 6 squared, which is 85 minus 36 to give 49. Taking the square root gives a half-length of 7 cm, so the full chord is 14 cm.