$(20$ pts$.)$ A circus performer is shot out of a cannon and flies over a vertical net that is placed at a horizontal distance of $9\mathrm{.}0$ m from the cannon. When the cannon is aimed at an angle of $39$ above the horizontal, the performer is moving in the horizontal direction and just barely clears the net as he passes over it$.$

a$)$ What is the muzzle speed of the cannon, and b$)$ how high is the net?