Question

what is the principal value of the following
$1.{ \cos( \frac{ \sqrt{3} }{2} ) }^{ - 1} \\ \\ 2.{ \csc(2) }^{ - 1} \\ \\ 3. { \cos( \frac{ - 1}{2} ) }^{ - 1}$
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Answer 1

Answer:

please refer the above attachment