1. The problem statement, all variables and given/known data Find the length of the curve r=cosΘ - sinΘ, 0≤Θ≤∏/4 2. Relevant equations Arc length = ∫|v| dt 3. The attempt at a solution I found r'(θ), then used the arc length formula. Arc length = ∫ sqrt (sin^2 Θ + cos^2 Θ) = ∫ dΘ and integrated it to find ∫dΘ = ∏/4 The correct answer is however ∏/(2sqrt(2)). Where did I go wrong?