I think a 75 gal tank for a single yellow tang is way OTT.
A 48"x12"x12" is plenty big for anything up to 6".
Smaller water volume means you can do 25% daily water changes with a single bucket, if you need to..... this is much more difficult in a bigger tank.
I treated an emporer angel, 5 yellow tangs, a purple tang and 6 anthias in a 75 gal tank for 6 weeks with hypo salinity........ it was far from ideal, I am quite experienced, and it was hard work.... definitely not to be recommended, especailly for a begginer....... but it shows that it can be done.....
I use a 48"x12"x12" an find it ideal....... But even for a yellow tang, maybe a 36"x15"x15" tank would be perfect.....
Now if you want to q-tine them all together, thats different...... but I would recommend individuals, or two at a time maybe, at most.......
HTH
Matt