please help!!

For an acute angle x, tanxtan(x/2)

cscx-1
secx-1
secx+1

Question

please help!!

For an acute angle x, tanxtan(x/2)

cscx-1
secx-1
secx+1

hartnn · Answer

you know tan double angle formula ?

ttop0816 · Answer

yes it is 2tan theta/1-tan^2theta!

hartnn · Answer

correct
so
tan x =  tan 2(x/2)
          = ....

hartnn · Answer

tanx tan(x/2) = 2 tan^2 (x/2) / (1+ tan^2 (x/2))

see if you get this ?

hartnn · Answer

*****
tanx tan(x/2) = 2 tan^2 (x/2) / (1- tan^2 (x/2))

hartnn · Answer

if you could get that, convert everything into sin and cos

ttop0816 · Answer

oh okay wait let me convert it!

ttop0816 · Answer

ummmm i got a really weird answer;; but i tried solving the whole thing and i got cscx-1

hartnn · Answer

is the question really tanx tan(x/2) ??

ttop0816 · Answer

yes HAHAHAHA

hartnn · Answer

from the given choices, i think its sec x -1

ttop0816 · Answer

oh okay! thank you~

hartnn · Answer

from the simple fact that tan x tan x/2 is 0 when x =0 

and only sec x - 1 becomes 0 when x = 0