transform f(x)=8+11cos π/7 (x-2) so that x is in terms of y

Answer 1

y = 11 cos [(π/7)(x - 2)] + 8

y - 8 = 11 cos [(π/7)(x - 2)]

(y - 8) / 11 = cos [(π/7)(x - 2)]

arccos [(y - 8) / 11] = (π/7)(x - 2)

{arccos [(y - 8) / 11]} / (π/7) = x - 2

({arccos [(y - 8) / 11]} / (π/7)) + 2 = x