first of all, you're combining your equations. the area of a triangle in this case is not .5 base x height sin(ang), it's .5 (side a) (side b) sin (ang). to find the side, just plug your values in and you should have only 1 unknown.
I got 10.0087
sin(73) * 0.5 * 7 * b= 33.5
33.5/sin(73) * 0.5 * 7 =b
I think i'm right, check me and let me know if my math is wrong.