# trigo help!

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**I'm stumped**
.

1. differentiate cos(3/x)

2. differentiate sin(4/x)

3. differentiate 3/{sin(3x+pi)}

4. differentiate pxsin(q/x)where p and q are constants.

5. differentiate xsin(a/x) where a is constant

6. differentiate sec^3(3x^2+1)