I'm having trouble with this question. Normally i would use auxiliary method but I'm having difficulty. Thanks in advance.
(i) Express 2cosθ + 2cos(θ + π∕3) in the form Rcos (θ + α), where R > 0 and, 0 < α < π/2
(ii) Hence, or otherwise, solve 2cosθ + 2cos(θ + π∕3) = 3, for 0 < α < 2π