(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° ; (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.