The radius of the co-centric circles are...........

The radii of two co-centric circles are 13 cm and 8 cm respectively. AB is diameter of outer circle and BE is tangent to the inner circles which touches the inner circle at point D. Then find the length of AD.

The sum of the radii of two concentric circles is 48. If a chord of length 36 of the larger circle is cut into three equal pieces by the smaller circle,then the radius of the larger circle is centric circles is

A sector OABO of central angle theta is constructed in a circle with centre O and of radius 6. The radius of the circle that is circumscribed about the triangle OAB, is 6cos(theta)/(2) (b) 6sec(theta)/(2)3sec(theta)/(2)(d)3(cos(theta)/(2)+2)

The adjoining figure shows two circles with the same centre.The radius of the larger circle is 10cm and the radius of the smaller circle is 4cm.

The area enclosed between the concentric circles is 770cm^(2). If the radius of the outer circle is 21cm, find the radius of the inner circle.

Two circles have an external tangent with length 36cm. The shortest distance between these circles is 14cm. If the radius of the longer circle is 4 xx the radius of the smaller circle then the radius of the larger circle in cms is

In the following diagram there are three circles packed in another circle, such that each circle is tangent to all other circles in this arrangement. The radius of the circumscribing circle A is 1 cm, and circle B and circle C are congruent. Find the radius of the circle D.

The radius of a circle is 20 cm. Three more concentric circles are drawn inside it in such a manner that it is divided into 4 equal parts. Find the radius of the smallest circle ?

The radius of circle A is twice that of circle B and the radius of circle B is twice that of circle C. Their area will be in the ratio