Calculate the line integral of the vector-function F(x, y, z) = (y² + z²) i − yzj + xk along the path L: x=t, y=2 cost, z = 2 sint (0≤1≤). Present your answer in the exact form (don't use a calculator). Rubric: 6 marks if the differential dr has been calculated correctly; 8 marks if the vector-function has been calculated correctly in terms of t; 6 marks if the dot-product has been correctly calculated; 12 marks if the integration was correct; 3 marks if the result has been correctly presented in the exact form.