(a) In Fig.-2, if a circle touches the side QR of △PQR at S and extended sides PQ and PR at M and N, respectively, then ‌ prove that ‌PM=‌

1

2

(PQ+QR+PR)
OR
(b) In Fig. 3, a triangle ABC is drawn to circumscribe a circle of radius 4 cm such that the segments BD and DC into which BC is divided by the point of contact D are of lengths 6‌cm and 8‌cm respectively. If the area of △ABC is 84cm2, find the lengths of sides AB and AC.