- Exam
- JEE Advanced
- Year
- 2022
- Paper
- Paper 1
- Subject
- Mathematics
- Chapter
- Trigonometric Equations
JEE Advanced 2022 · Paper 1 · Mathematics · Trigonometric Equations
Let |M| denote the determinant of a square matrix M . Let g: [0,...
Let be a quadratic polynomial whose roots are the maximum and minimum values of the function , and . Then, which of the following is/are TRUE ?
Options
- A
- B
- C
- D
Correct answer
A.
Step-by-step solution
Given,
f\left(\theta\right) = \dfrac{1}{2}\left|\begin{cases}1 & sin\theta & 1 \\ - sin\theta & 1 & sin\theta \\ - 1 & - sin\theta & 1\end{cases}\right| + \left|\begin{cases}sin\pi & \cos \left(\theta + \dfrac{\pi}{4}\right) & \tan \left(\theta - \dfrac{\pi}{4}\right) \\ \sin \left(\theta - \dfrac{\pi}{4}\right) & - cos\dfrac{\pi}{2} & \log_{e}\left(\dfrac{4}{\pi}\right) \\ \cot \left(\theta + \dfrac{\pi}{4}\right) & \log_{e}\left(\dfrac{\pi}{4}\right) & tan \pi\end{cases}\right|
⇒ f\left(\theta\right) = \dfrac{1}{2}\left|\begin{cases}1 & sin\theta & 1 \\ - sin\theta & 1 & sin\theta \\ - 1 & - sin\theta & 1\end{cases}\right| + \left|\begin{cases}0 & \cos \left(\theta + \dfrac{\pi}{4}\right) & \tan \left(\theta - \dfrac{\pi}{4}\right) \\ \sin \left(\theta - \dfrac{\pi}{4}\right) & 0 & \log_{e}\left(\dfrac{4}{\pi}\right) \\ - \tan \left(\theta - \dfrac{\pi}{4}\right) & - \log_{e}\left(\dfrac{4}{\pi}\right) & 0\end{cases}\right|
Here we used
And
And
Also
So, ⇒ f\left(\theta\right) = \dfrac{1}{2}\left|\begin{cases}1 & sin\theta & 1 \\ - sin\theta & 1 & sin\theta \\ - 1 & - sin\theta & 1\end{cases}\right| + \left(\text{skew symmetric}\right)
So,
Now maximum and minimum values are and respectively.
Now quadratic polynomial will be , where ,
But given , so .
Now solving all options we get,