Find the value of
.
We know that, 
and
[since, cos 
]
[since, tan-1 (-x)=- tan-1 x, x ∈ R and cos-1 (-x)=π-cos-1 (x), x ∈(-1, 1)]
[since, cos 
]
3
Find the value of.
We know that, and
[since, cos ]
[since, tan-1 (-x)=- tan-1 x, x ∈ R and cos-1 (-x)=π-cos-1 (x), x ∈(-1, 1)]
[since, cos ]