Answer (Detailed Solution Below)

Option 4 : -2/x
Free
NDA 01/2025: English Subject Test
30 Qs. 120 Marks 30 Mins

Detailed Solution

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Concept:

Trigonometry:

  • .
  • sin2 θ + cos2 θ = 1.

 

Calculus:

Chain Rule of Derivatives:

  • .

 

Calculation:

Let v =  and u = .

Substituting x = cos θ ⇒ θ = cos-1 x, we get:

v =  

= csc-1 (sec 2θ) = csc-1 (csc (90 - 2θ))

= 90 - 2θ.

And, u =  

u = sin θ.

Now,  = -2 and  = cos θ.

∴ 

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