Question

plse explain this
and solve

Answer 1

its just a formula \[\cos^{-1} (cosx) = x\]

Answer 2

and also cos cannot exist beyond \[\pi and 5\pi/4\]

Answer 3

is \[\pi + \pi/4\]

Answer 4

so its undefined i hope.

Answer 5

\[\cos \frac{5\pi}{4}=-\frac{\sqrt{2}}{2}\]
So now the problem becomes:
\[\cos^{-1} (-\frac{\sqrt{2}}{2})\]

Answer 6

And that means: give the angle between 0 and pi whose cosine is - sqrt2/2.
That angle is 3pi/4

Answer 7

so it is defined or not