Question

If radii of two concentric circles are 4 cm and 5 cm, then the length of the chord of one circle which is tangent to the other circle is:​

Answer 1

The length of chord is 6 cm.

Step-by-step explanation:

Since we have given that

Radius of small circle = 4 cm

Radius of large circle = 5 cm

So, we need to find the length of each chord of one circle which is tangent to the other circle.

Since it forms a right angle triangle.

So, it becomes,

So, Length of chord is given by

Hence, the length of chord is 6 cm.

Answer 2

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Here OC is perpendicular to AB.

Then OC bisects AB i.e., AC = BC

Now, in triangle OAC,

OA² = AC² + OC²

⇒ (5)² = AC²+ (4)² ⇒AC²=25-16

⇒AC = 3 Therefore, length of tangent AB=

AC + BC = 3 + 3 = 6 cm

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