Let $$\style{font-size:18pt}{f(t)=\sin(at)}$$ and $$\style{f…

Let $$\style{font-size:18pt}{f(t)=\sin(at)}$$ and $$\style{font-size:18pt}{g(t)=1,}$$ where $$\style{font-size:18pt}{a}$$ is a positive constant. (a) Use the definition of the convolution to show that $$\style{font-size:18pt}{(f\ast g)(t) = \dfrac{1}{a}\left( 1- \cos(at) \right).}$$(b) Use the result from (a) to find $$\style{font-size:18pt}{{\cal L}^{-1}\left[\dfrac{3}{s(s^2+2)}\right].}$$