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Which of the following is incorrect? - Mathematics

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Question

Which of the following is incorrect?

Options

  • \[\sin x = - \frac{1}{5}\]

     

  • cos x = 1

  • \[\sec x = \frac{1}{2}\]

     

  • tan x = 20

MCQ
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Solution

`bb(sec x = 1/2)`

Explanation:

\[\sin x = - \frac{1}{5}\] is correct as \[- 1 \leq \sin x \leq 1\]

cos x = 1 is correct as cos x = 1 is correct as

\[\sec x = \frac{1}{2}\] is not correct as \[\sec x \in ( - \infty , - 1] \cup [1, \infty )\]
tan x = 20 is correct as tan x can take any real value.
Hence, the correct answer is option \[\sec x = \frac{1}{2}\].
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Chapter 5: Trigonometric Functions - Exercise 5.5 [Page 43]

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RD Sharma Mathematics [English] Class 11
Chapter 5 Trigonometric Functions
Exercise 5.5 | Q 25 | Page 43

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