It is known that cosx = - radical 3 / 3 and 18O degree

It is known that cosx = - radical 3 / 3 and 18O degree

cosx =-√3/3
sinx = -√6/3
tanx = sinx/cosx =√2
sin2x= 2sinxcosx =2√2/3
cos2x = (cosx)^2- (sinx)^2 = -1/9
tan2x= 2tanx/(1-(tanx)^2) = 2√2/ (1-2) =-2√2