In △ABC, let AD be the median to side BC. In △PQR, let PS be the median to side QR. It is given that AD=9cm, PS=6cm, and BC=15cm. Further, ∠A=∠P and ∠C=∠R.
(a) Prove that △ABC∼△PQR.
(b) Using part (a), calculate the length of QR.
(c) If AB=13cm, determine PQ.
(d) Find the ratio [△ABC]:[△PQR].