If for a perfectly competitive firm, price is Rs 7.2, output is 4500 units, average variable costs are Rs 1.2, and average total costs are Rs 4. The firm's profits are equal to
Two circles of same radius intersect each other at P and Q. If the length of the common chord is 30 cm and distance between the centres of the two circlesis 40 cm, then what is the radius (in cm) of the circles?