question_answer

The equation of tangent to the curve \[y=2\cos x\,\,at\,\,x=\frac{\pi }{4}\] is

A)  \[y-\sqrt{2}=2\sqrt{2}\,\,\left( x-\frac{\pi }{4} \right)\]

B)  \[y+\sqrt{2}=\sqrt{2}\,\,\left( x-\frac{\pi }{4} \right)\]

C)  \[y-\sqrt{2}=-\sqrt{2}\,\,\left( x-\frac{\pi }{4} \right)\]

D)  \[y-\sqrt{2}=\sqrt{2}\,\,\left( x-\frac{\pi }{4} \right)\]

E)  None of these