Prove the identity tan pi x tan x Note that each Statement
     Prove the identity.  tan (pi - x)= -tan x  Note that each Statement must be based on a Rule chosen from the Rule mark.   
  
  Solution
tan x ( 1+ cos 2x ) = sin 2x
cos 2x = cos^x - sin^2 x
sin 2x = 2 sin x cos x
tan x = sin x / cos x
sin x / cos x ( 1 + cos^-x - sin^2 x)
proving left hand side
sin x / cosx ( sin^2 x + cos^2 x + cos^2x - sin^2x )
sin x / cos x ( 2 cos^2 x )
2 sin x cos x = 2 sin x cos x or sin 2x
left hand side = right hand side
proved

