Question

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

Options

• 3 cm

• 6 cm

• 9 cm

• 1 cm

Answer 1

If radii of two concentric circles are 4 cm and 5 cm, then the length of each chord of one circle which is tangent to the other circle is 6 cm.

Explanation:

Given,

OA = 4 cm, OB = 5 cm

And, OA ⊥ BC

Therefore, OB² = OA² + AB²

⇒ 5² = 4² + AB²

⇒ AB = `sqrt(25 - 16)` = 3 cm

⇒ BC = 2AB = 2 × 3 cm = 6 cm