Locus questions tell you to sketch. They don't ask for anything else as far as I know.
And working out suggests using the algebraic method...although for this type of question, a geometric approach is much simpler.
Perhaps you could tell me how to post up the answer properly like you always do...rather than uploading to imageshack and ending up with a black picture...
My opinion is that you have to be great at 3U (and finished the course for things such as motion, polynomials) in order to do 4U...otherwise it gets too tedious.
Well I've finished the course so I have nothing to say about where the school is up to....but how can particular schools do Volumes without doing Integration first?