Book: RD Sharma - Mathematics (Volume 1)
Chapter: 4. Inverse Trigonometric Functions
Subject: Maths - Class 12th
Q. No. 3 of Exercise 4.3
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3
Evaluate each of the following:
Firstly, tan
= tan
……(i)
Also, cos
cos
cos 
……(ii)
From (i) and (ii),
becomes,
Now,
We know that, for any x 
R, 
represent an angle in 
whose tangent is x.
We know that, for any x 
[-1, 1], 
represent an angle in 
whose cosine is x.
Hence, 
Therefore, Principal Value of 
is 0.
