# Thread: Find the value of 'trig of inverse trig' questions

1. ## Find the value of 'trig of inverse trig' questions

Evaluate each expression

tan(arccos(2/2))

cos(arcsin(5/13))

2. Originally Posted by sydewayzlocc
Evaluate each expression

tan(arccos(2/2))

cos(arcsin(5/13))
$tan(arccos(\frac{\sqrt2}{2})) = tan(\frac{\pi}{4}) = 1$

what you need to notice: $cos(\frac{\pi}{4}) = \frac{\sqrt{2}}{2}$

what you need to remember: $arccos(cos(x)) = cos^{-1}(cos(x)) = x$

$\therefore arccos(cos(\frac{\pi}{4})) = arccos(\frac{\sqrt{2}}{2})$

so, $\frac{\pi}{4} = arccos(\frac{\sqrt{2}}{2})$

Try the second one.