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
(A) 3 cm (B) 6 cm (C) 9 cm (D) 1 cm
Answer (B) 6 cm
Solution
According to question
Here A is the center and AB = 4 cm radius of small circle and AD = 5 cm radius of large circle.
We have to find the length of CD
ABD is a right angle triangle.
Hence use Pythagoras theorem in ABD
Hence length of chord is 6 cm.