Question

When n is an odd natural number other than 1, then the value of x is

• A. $-\pi /2$
• B. 0
• C. $\pi$
• D. $3\pi$

Answer 1

Answer: (A), (B)

The correct options are
A $-\pi /2$
B 0

For this question its better to check options,
option A,
$co{s}^n\left(\frac{-\pi }{2}\right)=0,si{n}^n\left(\frac{-\pi }{2}\right)=-1$, since n is odd natural number
Hence option A is correct
option B,
$co{s}^n\left(0\right)=1,si{n}^n\left(0\right)=0$
Hence option B is correct
option C,
$co{s}^n\left(\pi \right)=-1,si{n}^n\left(\pi \right)=0$, since n is odd natural number
Hence option C is incorrect
option D,
$co{s}^n\left(3\pi \right)=-1,si{n}^n\left(3\pi \right)=0$, since n is odd natural number
Hence, option 'D' is incorrect