what is the exact value of tan(arccos((x-1)/8)) after you get to sqrt((x+7)(-x+9))/(x-1)

2 answers

Huh? That is the exact value.
That's what I got
or
you could have left it as
√(63 +2x - x^2)/(x-1)

test it with your calculator , by picking something like x = 3.5, make sure your calc is in radians
(worked for me)