If x = cos t + log tan Differentiating with respect to t ⇒ ⇒ ⇒ ⇒ Differentiating with respect to x ⇒ ⇒ ⇒ 
, 
[Putting t = π /4 ]
[Putting t = π /4 ]
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If x = cos t + log tan Differentiating with respect to t ⇒ ⇒ ⇒ ⇒ Differentiating with respect to x ⇒ ⇒ ⇒ , [Putting t = π /4 ] [Putting t = π /4 ]