1. The problem statement, all variables and given/known data I am told to find out the length of he curve y=¼x^2 2. Relevant equations The length of the curve should be ∫√(1+¼x^2)dx 3. The attempt at a solution I substituted tanx and got ∫2/cos^3x dx So how could I continue and work out the solution? Should I use integration by part, or I had already done wrong?