Question

Evaluate the following expressions

tan(−22/15π)

Answer 1

tan(-22/15π)
-tan(22/15π)
-tan(π+7/15π)
-tan(7/15π)
not a recognizable value. As long as you have to use your calculator anyway, why nut just plug in the original value? You get -9.514

Or is there more to the question than what you posted?

Answer 2

There is more to it...
Find the exact value

tan^-1(tan(-22/15pi))

I just could not figure out how to find an exact value for tan(-22/15pi)

Answer 3

You don't need it.
arctan(-x) = -arctan(x)
So, now you want

arctan(-tan(7/15π))
= -arctan(tan(7/15π))
= -7/15π