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The most general solution of the equations \tan \theta = -1 , \cos \theta = 1/ \sqrt 2is

Option: 1

n \pi + 7\pi /4


Option: 2

n \pi +(-1)^n \: \: 7\pi /4


Option: 3

2n \pi + 7\pi /4


Option: 4

none 


Answers (1)

best_answer

   As we have learnt in

 

General Solution of Trigonometric Ratios -

\cos \Theta = \cos \alpha

\Theta = 2n\pi \pm \alpha , n\epsilon I

- wherein

\alpha is the given angle

 

 

General Solution of Trigonometric Ratios -

\tan \Theta = \tan \alpha

\Theta = n\pi + \alpha , n\epsilon I

- wherein

\alpha is the given angle

 

 

   We have   \tan \theta = -1 \: \: and \: \: \cos \theta = 1/ \sqrt 2

The value of \theta lying between 3 \pi /2 \: \: and \: \: 2 \pi and satisfying these two is 7\pi /4. Therefore the most general solution is   \theta = 2n \pi + 7 \pi /4    where n \epsilon Z.

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rishi.raj

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