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Find the principal values of the following: cosec- 1(2) - Mathematics and Statistics

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Question

Find the principal value of the following: cosec- 1(2)

Sum
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Solution

The principal value branch of cosec-1x  is `[- pi/2, pi/2] - {0}`.

Let cosec-1(2) = α, `"where" (-pi)/(2) ≤ α ≤ pi/(2)`, α ≠ 0.

∴ cosec α = 2 = `"cosec"  pi/(6)`

∴ α = `pi/(6)                  ...[ ∵ - pi/2 ≤ pi/6 ≤ pi/2 ]`

∴ the principal value of cosec-1(2) is `pi/(6)`.

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Chapter 3: Trigonometric Functions - Exercise 3.3 [Page 102]

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