If you divide 5sin(2x+40) by root3cos(2x+40) you end up with 5/root3 multiplied by sin(2x+40)/cos(2x+40) = 1, since the trig identity means that any sin over cos makes tan, then you have 5/root3 multiplied by tan(2x+40) = 1, then times both sides by root3, then divide by 5 and u end up with tan(2x+40) = root3/5