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A chord is at a distance of 15 cm from the centre of the circle of radius 25 cm. The length of the chord is

#### Options

25 cm

20 cm

40 cm

18 cm

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#### Solution

**40 cm**

**Explanation;**

Hint:

In the right triangle OAC,

AC^{2} = OA^{2} – OC^{2}

= 25^{2} – 15^{2}

= (25 + 15)(25 – 15)

= 40 × 10

AC^{2} = 400

AC = `sqrt(400)`

= 20

Length of the chord AB = 20 + 20 = 40 cm.

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