Hey there! I'm trying to calculate the Fourier Series for sin2x on [-π, π] For a0 I found 1/2. (By determining the average value of the function on the interval) Since sin2x is even, I know that bn = 0. Now, for an.. The following link shows the integral I used to try to evaluate an. http://www.wolframalpha.com/... Since an and bn are both coming out to be zero, doesn't this imply that sin2x = a0 = 1/2? Will someone please show me where I am going wrong? Can't find anything online about this. Everyone just always uses the sin2 identity and calls it good.