Background: CS Undergrad applying to CS PhD (USA)
My CV is 2 pages long. The second page is only half filled.
Question: Should I add two short sentences regarding my research interests? (at the end)
*Note: I already have an online website which has the same explained in more detail.
A research statement is usually a longer document describing what research you did, why you did it, why it's important, and what you want to do in the future. While your CV should just be about stating the facts about your career, your education, achievements etc. So, no, I would not put a research statement in a CV
However you should add a section listing your research projects (completed and ongoing). Example:
(2019-2020) 3rd year Bsc project: Designing a new algorithm to do X.
(2019) Summer project: Built a web app to do Y.
If you craft the description right, you can explain very succinctly what you did, without it becoming a research statement.
Don't worry about the length of the CV, you are applying for a PhD so it's expected that it won't be very long.
I'm not sure I have ever not just skipped straight over any substantial body of writing in a CV. A CV is a data source, not an interpretive document. I go to a CV to answer specific questions (What degree does this person have? do they have any research experience? Have they ever held down a job? etc).
An application for a PhD would normally include a separate cover letter where you can explain what you are applying for this PhD and how it fits perfectly with your previous interests.
