Question

If and are the radi of two concentric circles and (r. > r.). If the chord

of the larger circle AB touches the inter circle. Find the value of AB​

Answer 1

r1 and r2 are the radii of two concentric circles

To find:

The length of the chord of the larger circle.

Solution:

We have given the two concentric circles which means both the circles have the same centre.

The chord of the larger circle toches the inner circle so the chord of the larger circle will be the tangent of the smaller circle.

And we know that the radius of the circle is perpendicular to the tangent of the circle.

Let 2x be the length of the chord of the circle.

r1 is the radius of the larger circle.

r2 is the radius of the smaller circle.

So by the Pythagoras theorem,

The length of the half of the chord is given by:

r1² = x² + r2²

x² = r1² - r2²

x = √r1² - r2²

So,

The length of the chord will be 2x = 2√r1² - r2² units

Explanation: