Answer:
720/1681
Step-by-step explanation:
First quadrant so everything is positive for a trig function of just the angle. I would suggest just drawing a right triangle using tan(x)=40/9 (opp/adj). Find the hypotenuse which is sqrt(40^2+9^2)=sqrt(1600+81)=sqrt(1681)=41. So sin(x)=40/41 and cos(x)=9/41.
Therefore sin(2x)=2sin(x)cos(x)=2(40/41)(9/41)=720/1681
