A chord of length 42 cm is drawn in a circle having diameter 58 cm. What is the minimum distance of other parallel chord of length 40 cm in the same circle from 42 cm long chord?

In a circle, two chords, AB and CD, measuring 14 cm and 6 cm, respectively, are parallel to each other on the same side of the centre. If the distance between them is 4 cm, find the length (in cm) of the diameter of the circle.​

POR is the diameter of a circle. PQ and RQ are its two chords. The length of are $$\overline{PQ}$$ is half of the length of are $$\overline{RQ}$$. Find the measure of ∠POQ.​