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A chord of length 48 cm is at a distance of 10 cm from the centre of a circle. If another chord of length 20 cm is drawn in the same circle, find its distance from the center of the circle.

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Answer

From figure,

A chord of length 48 cm is at a distance of 10 cm from the centre of a circle. If another chord of length 20 cm is drawn in the same circle, find its distance from the center of the circle. Circle, ML Aggarwal Understanding Mathematics Solutions ICSE Class 9.

Since, OM ⊥ AB, it bisects it. (As perpendicular from center to chord bisects it)

∴ AM = MB = 482\dfrac{48}{2} = 24 cm.

In right △AOM,

⇒ AO2 = OM2 + AM2 (By pythagoras theorem)

⇒ AO2 = 102 + 242

⇒ AO2 = 100 + 576

⇒ AO2 = 676

⇒ AO = 676\sqrt{676} = 26 cm.

Radius = 26 cm.

Since, ON ⊥ CD, it bisects it. (As perpendicular from center to chord bisects it)

∴ CN = ND = 202\dfrac{20}{2} = 10 cm.

In right △CNO,

⇒ OC2 = ON2 + NC2 (By pythagoras theorem)

⇒ 262 = ON2 + 102

⇒ ON2 = 676 - 100

⇒ ON2 = 576

⇒ ON = 576\sqrt{576} = 24 cm.

Hence, the chord of length 20 cm is at a distance of 24 cm from the centre.

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