MCQ
Which of the following is incorrect?
- A$\sin\text{x}=-\frac{1}{5}$
- B$\cos\text{x}=1$
- C$\sec\text{x}=\frac12$
- D$\tan\text{x}=20$
Solution:
$\sin\text{x} = -\frac{1}{5}$ is correct as $-1\leq \sin\text{x} \leq1$
$\cos\text{x}=1$ is correct as $-1\leq \cos\text{x}\leq1$
$\sec\text{x}=\frac{1}{2}$ is correct as $\text{x}\in [(-\infty, -1)\ \cup (1,\infty)]$
$\tan\text{x} = 20$ is correct as $\tan\text{x}$ can take any real value.
Hence, the correct answer is option C.
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For all n ∈ N, 3 × 52n+1 + 23n+1 is divisible by: