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

A vertical tower OP stands at the center O of a square ABCD. Let h and b denote the length OP and AB respectively. Suppose APB = 60^o then the relationship between h and b can be expressed as