NTA Abhyas 2020
- Exam
- NTA Abhyas
- Year
- 2020
- Subject
- Mathematics
- Chapter
- Inverse Trigonometric Functions
NTA Abhyas 2020 · Mathematics · Inverse Trigonometric Functions
If a _ 1 , a _ 2 , a _ 3 are in arithmetic progression and d is the...
If are in arithmetic progression and is the common difference, then
Options
- A
- B
- C
- D
Correct answer
A.
Step-by-step solution
Since, are in A.P.
Now, \left(\dfrac{d}{1 + {a}_{2}{a}_{3}}\right)<= \tan^{-1} \left(\dfrac{{a}_{2} - {a}_{1}}{1 + {a}_{1}{a}_{2}}\right) + \tan^{-1}
\left(∵ \tan^{-1}x - \tan^{-1}y = \tan^{-1}\dfrac{x - y}{1 + xy}\right)= \tan^{-1} {a}_{2} - \tan^{-1} {a}_{1} + \tan^{-1} {a}_{3} - \tan^{-1} {a}_{2}{= tan}^{- 1} {a}_{3} - \tan^{-1} {a}_{1}= \tan^{-1} \left(\dfrac{{a}_{3} - {a}_{1}}{1 + {a}_{1}{a}_{3}}\right)
=\tan^{-1}
=\tan^{-1}
Now, \left(\dfrac{d}{1 + {a}_{2}{a}_{3}}\right)<= \tan^{-1} \left(\dfrac{{a}_{2} - {a}_{1}}{1 + {a}_{1}{a}_{2}}\right) + \tan^{-1}
\left(∵ \tan^{-1}x - \tan^{-1}y = \tan^{-1}\dfrac{x - y}{1 + xy}\right)= \tan^{-1} {a}_{2} - \tan^{-1} {a}_{1} + \tan^{-1} {a}_{3} - \tan^{-1} {a}_{2}{= tan}^{- 1} {a}_{3} - \tan^{-1} {a}_{1}= \tan^{-1} \left(\dfrac{{a}_{3} - {a}_{1}}{1 + {a}_{1}{a}_{3}}\right)
=\tan^{-1}
=\tan^{-1}