5.Find the Fourier series of the saw tooth wave function $$f(x)=x+\pi, \text{ if } -\pi

9.If the vectors $\vec{v}(t) = 4t\vec{i} + 5t^3\vec{k}$ and $\vec{w}(t) = t^2\vec{i} - 5t\vec{j} + 2t^3\vec{k}$. Find $$\frac{d}{dt}(\vec{w} \cdot \vec{v}) \quad (10\%)$$ and $$\frac{d}{dt}(\vec{v} \times \vec{w}) \quad (10\%)$$