Posted by al on .
lim_(theta>0)(cos(6 theta)tan(6 theta))/(theta)

calculus 
MathMate,
lim_(theta>0)(cos(6 theta)tan(6 theta))/(theta)
=Lim (θ→0)[cos(6θ)sin(6θ)/cos(6θ)]/θ
=Lim [6 (sin(6θ)/6θ)]
=Lim [6*1]
=6
Note:
Lim sin(x)/x =1
x→0