RD Sharma - Mathematics (Volume 1)

Book: RD Sharma - Mathematics (Volume 1)

Chapter: 4. Inverse Trigonometric Functions

Subject: Maths - Class 12th

Q. No. 2 of Exercise 4.7

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2

Evaluate each of the following:

cos–1(cos 5)

cos–1(cos x) = x


Provided x ϵ [0,π] ≈ [0,3.14]


And in our equation x is 5 which does not lie in the above range.


We know cos[2π – x] = cos[x]


cos(2π – 5) = cos(5)


Also 2π–5 belongs in [0,π]


cos–1(cos 5) = 2π–5


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