Find out the number of ways in which 6 rings of different types can be worn in 3 fingers?

In the figure below, the rectangle at the corner measures 10 cm 20 cm. The corner A of the rectangle is also a point on the circumference of the circle. What is the radius of the circle in cm?

In the figure given below, AB is the chord of a circle with center O. AB is extended to C such that BC = OB. The straight line CO is produced to meet the circle at D. If ACD = y degrees and AOD = x degrees such that x = ky, then the value of k is