Attempt the question, check the explanation, and continue with similar questions to build confidence before exams.
√((x2-x1)^2 + (y2-y1)^2)
√((x1+x2)^2 + (y1-y2)^2)
x2-x1 + y2-y1
x1 + y1
Continue with nearby questions to strengthen the same chapter concept while you still have the context fresh in mind.