How do I find the x value of an undefined tangent function

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Apologies in advance if the formatting for the equations isn't great (first time doing this), hopefully it worked correctly though.

The problem:

Given the function $f(x)=-2*\tan(1.7*x-8.8)-7.7$ find the x value which is (a) undefined and (b) a x value at which $f(x)=0$

I have already found the undefined value by calculating $1.7*x-8.8$=$\frac{(\pi)}{2}$ which gave me $6.1005$

To find an x value at which $f(x)=0$, I tried entering the equation as:

$0=-2*tan(1.7*(6.1005)-8.8)-7.7$

$\ln(0)=\ln(-2*tan(1.7*(6.1005)-8.8)-7.7)$

and carrying it through from there however my answer kept coming back as either false or undefined. Can someone help me with this? Its probably really simple but I cant think of any other way aside from the natural log method

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You've done the first half. For $f(x) = 0 \implies -2\tan(1.7x - 8.8) = 7.7\implies \tan(1.7x-8.8) = -\dfrac{7.7}{2}=-3.85\implies 1.7x-8.8=\tan^{-1}(-3.85)\approx-1.32\implies x \approx\dfrac{8.8-1.32}{7.7}\approx 0.97$.