Originally Posted by

**zhangxupage2** Hi everyone. I'm working on a calc problem, but I found it to be difficult. Maybe I'm missing the point.

Find the equation of the tangent line to the graph of $\displaystyle f(x)=3x tan^2(x) + x^2 cos(x)$

Well, this is the derivative I got:

$\displaystyle 3tan^2(x)+6tan(x)sec^2(x) + 2xcos(x)-x^2sin(x)$

Since it just says the equation of the line, but it doesn't specify an x-value, so I just plug in a random value. However, I found it extremely difficult to do it the regular way, because trig functions are involved.

Is there a trick to solve this problem?

Thanks a lot.