From an external point P two tangents PA and PB are drawn to a circle with centre O and radius 3cm. The length of each tangent from P is 4cm. From another external point Q, situated farther from O, two tangents of length 6cm are drawn to the same circle.
(i) Find the distance OP.
(ii) Find the distance OQ.
(iii) Calculate the difference between OQ and OP.
c. (iii) Calculate OQ−OP.