(a) Using a ruler and a pair of compasses only, construc : (i) a triangle PQR such that /PQ/ = 10 cm, /QR/ = 7 cm and < PQR = 90^\circ ; (ii) the locus \(l_{1}\) of points equidistant from Q and R ; (iii) the locus \(l_{2}\) of points equidistant from P and Q. (b) Locate the point O equidistant from P, Q and R. (c) With O as centre, draw the circumcircle of the triangle PQR. (d) Measure the radius of the circumcircle.