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Consider the following statements I. ...

Consider the following statements
I. sin |x| + cos |x| is always positive
II. `sin(x^2) + cos (x^2)` is always positive
Which of the above statement is/are correct?

A

A) Only I

B

B) Only II

C

C) Both I and II

D

D) Neither I nor II

Text Solution

AI Generated Solution

The correct Answer is:
To determine the correctness of the given statements, we will analyze each statement step by step. ### Step 1: Analyze Statement I **Statement I:** \( \sin |x| + \cos |x| \) is always positive. 1. The functions \( \sin |x| \) and \( \cos |x| \) are periodic functions with a period of \( 2\pi \). 2. The range of \( \sin |x| \) is between -1 and 1, and the range of \( \cos |x| \) is also between -1 and 1. 3. We need to find if there are values of \( x \) such that \( \sin |x| + \cos |x| \leq 0 \). 4. Consider \( x = \frac{3\pi}{2} \): - \( |x| = \frac{3\pi}{2} \) - \( \sin\left(\frac{3\pi}{2}\right) = -1 \) - \( \cos\left(\frac{3\pi}{2}\right) = 0 \) - Thus, \( \sin |x| + \cos |x| = -1 + 0 = -1 \), which is less than 0. 5. Therefore, Statement I is **not always positive**. ### Step 2: Analyze Statement II **Statement II:** \( \sin(x^2) + \cos(x^2) \) is always positive. 1. Similar to the first statement, \( \sin(x^2) \) and \( \cos(x^2) \) are also periodic functions. 2. The range of \( \sin(x^2) \) and \( \cos(x^2) \) is also between -1 and 1. 3. We need to check if there are values of \( x \) such that \( \sin(x^2) + \cos(x^2) \leq 0 \). 4. Consider \( x = \sqrt{\frac{3\pi}{2}} \): - \( x^2 = \frac{3\pi}{2} \) - \( \sin\left(\frac{3\pi}{2}\right) = -1 \) - \( \cos\left(\frac{3\pi}{2}\right) = 0 \) - Thus, \( \sin(x^2) + \cos(x^2) = -1 + 0 = -1 \), which is less than 0. 5. Therefore, Statement II is **not always positive**. ### Conclusion Both statements I and II are not always positive. Thus, the correct answer is that neither statement is correct. ### Final Answer **Neither Statement I nor Statement II is correct.** ---
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