Firstly, I'm sorry if this has been asked before or if this is not the right place for this question but I couldn't find the answer anywhere. My question is wether or not extension 2 students are allowed to use extension 2 techniques in the extension 1 HSC paper? For example, when calculating volume of a solid of revolution which is rotated about the y-axis, can I just use cylindrical shells instead of dealing with changing the dy -> dx method that is learned in extension 1? Thanks in advance!