Question

20 points helppppppppppppppppppppppppppppp

PLZZ anyone solve this ASAP​

Answer 1

`cos^(-1)(cos( 7π)/(6))=cos^(-1)(cos(7*180)/(6))`

`cos^(-1)(cos{210})`

`cos^(-)(cos(180+30))`

[since in third quadrant cos 30=-
`(√(3))/(2)]`

`cos^(-)(- (√(3))/(2))`

:150°or
`(5π)/(6)`

150°or
`(5π)/(6)`is a required answer.