Alan or Bertie can you please talk me through this. I can't bet my head around it :(
sec(Tan^-1(x))= -2/sqrt3
let tan^-1x=theta
then
tan (theta)=x
\(sec(\theta) = \sqrt{1+x^2}\)
now it doesn't matter if x is positive or negative sec(theta) has to be positive. SO
I don't think that there should be any solutions.
Here is a graph to back up what I am saying
https://www.desmos.com/calculator/dutfolqi6o
This page also seems to back up what I am saying
http://www.wolframalpha.com/input/?i=sec%28Tan%5E-1%28x%29%29
BUT
Look at this weird output
http://www.wolframalpha.com/input/?i=sec%28Tan%5E-1%28x%29%29%3D-2%2Fsqrt3
and this one
http://www.wolframalpha.com/input/?i=sec%28Tan%5E-1%28x%29%29%2B2%2Fsqrt3%3D0
I am so confused :((