The Cartesian coordinate components of the metric tensor and the Ricci tensor in the flat Friedmann space-time are given by 9μν 1 0 0 0 0 a(t)2 0 0 0 0 a(t)2 0 0 0 0 a(t)2 -3ä 0 0 a 0 c-2 (aä + 2a2) 0 0 0 c-2 (aä + 2a2) 0 0 0 Rμν = 0 0 0 c-2(aä + 2a2) where a(t) is a function of time known as the scale factor. Using the rules for raising and lowering indices in general relativity: a) Determine the R 11 component of the Ricci tensor. b) Using the above result, determine the component R11 of the Ricci tensor.