Saturday, 21 February 2015

trigonometry - How to prove that cscx2cosxcot2x=2sinx



My idea was...



LHS=1sinx2cosxtan2x=tan2xsin2xsinxtan2x



from here, I don't know how to continue, please help! thanks



ps, please teach me how to use the "divide" symbol


Answer



Somewhere you'll need a double-angle formula:
tan(2x)=2tanx1tan2x
or
tan(2x)=sin(2x)cos(2x)=2sinxcosxcos2xsin2x.


No comments:

Post a Comment

real analysis - How to find limhrightarrow0fracsin(ha)h

How to find lim without lhopital rule? I know when I use lhopital I easy get $$ \lim_{h\rightarrow 0}...