In the given figure, a circle is inscribed in Δ PQR, such that it touches the sides PQ, QR and RP at points D, E, F, respectively. If the lengths of the sides PQ = 15 cm, QR = 11 cm and RP = 13 cm, then find the length of PD.
1
9 cm
2
8 cm
3
7.5 cm
4
8.5 cm