The Student Room Group
for part a) divide both sides by cosx. this will give you

tan x= 3
x= arctan 3
part b) use the identity sin2x= 2sinxcosx

12sinxcosx= 3cosx

rewrite- 12sinxcosx- 3cosx= 0
factorise= 3cosx(4sinx- 1) =0

so 3cosx=0 and 4sinx-1 =0
Thank you
Reply 4
Posting here to remind myself to do part c later ...