differentiation of trig functions. help plz. (1 Viewer)

[Dio-Rama]

Find the gradient of the tangent to the curve y=tan3x
at the point where x= pi/9.

please help!!

 

[Trev]

y=tan3x
dy/dx=3sec²3x
when x=pi/9
dy/dx=3 * 1/[cos²(3*pi/9)]
= 3 * 1/[(1/2)²]
= 12.

 

[Dio-Rama]

thanx dude