Hello I have a question here which I've been thinking for quite sometime. And I am still very puzzled. It goes: Find the volume generate by the curve y=lnx rotating about the line y=x. Within the interval of x [4,10]. I would like to know the approach to this problem as I have been asking some of my lecturers how to do this. Some said for this question, it involves interpolation while some said double integration etc. Hope you can help me with this. Thankx!