1. The problem statement, all variables and given/known data E(t) = 100te1+cos((2π*t)/365 What is the derivative of this function? 2. Relevant equations 3. The attempt at a solution 100*e1+cos((2π*t)/365) + 100t*e1+cos((2π*t)/365) * -(2π/365)sin(2πt/365) I have tried to use the rules for derivative of products, and also used the chain rule.