Q.

The derivative of sin2x with respect to ecosx is:

1 2cosxecosx  
2 -2cosxecosx  
3 2ecosx  
4 None of these  

Ans.

(2)

Ans.     -2cosxecosx

Explanation:

Let  u(x)=sin2x  and  v(x)=ecosx. We want to find dudv.

Thus, dudv=dudxdvdx.  Clearly, dudx=2sinx cosx

and  dvdx=ecosx(-sinx)=-(sinx)ecosx

Therefore,  dudv=2sinxcosx-sinx ecosx=-2cosxecosx