I think the question is misprinted on the FP2 PAPER?Watch
Q5 appears to calculate the region R as if it were bounded by the two curves. I think the mark scheme is wrong. I have attached my working below. If i am wrong could someone please point it out?
I thought if I substitute pi/2 into r=4sinx it would give me the radius but as I write this I realise I have calculated the diameter 🙄😂 and that explains why my attempt was probably wrong