Answer to Question #24682 in Trigonometry for Chris

Question

Use the double angled formula to prove the following expressions. (i) Given that cos(x+30)=3cos(x-30), prove that tanx= - root 3/ 2 (ii)prove that 1-cos2x/sin2x = tan x (iii) verify that x= 180 is a solution of the equation 2x=2-2cos2x (iv) Using the resulat from part (ii) or otherwise find the two other solutions

Had this previously answered to which I can solve parts 1 & 2 and expand upon them but I am a little confused with parts 3 and 4 ...

Can any one elaborate?

Thanks