Use Pythagoras' theorem:
152-92 = 144 and the square root of 144 is 12
Answer: 12 feet
Does "15 foot round" refer to Perimeter, Diameter or Radius.
Although it is a great achievement, I have heard of someone doing it at a local club. So yes, someone has achieved it before you.
It all depends, on pavement 2wd will do 90 of the time although if you like goin off road with your trailer it will help definitely to have the 4wheels turning. Most of the time i use 2wd I have a 15foot tandem car trailer. It is better to use the 2wd just so u can make the charp turns when you have to. It also isn't that great on the transferr case to drive on dry pavement. It whears them out in a hurry. So long story short you should just use your best judgment. If you need all wheels turning to get you going just do that but don't drive the whole trip in 4x4. Hope this helped you some.
16.8m212x15=180; ftxft = ft2. We have 180ft2, and there are 10.7639ft2 in 1m2. We need to divide 180 by 10.7639 since there are fewer m2. 180/10.7639 = 16.76 ...
for in-ground estimated costs are $7,000-$16,000 for a vinyl-lined model, $15,000-$25,000 for a fiberglass shell and $17,000-$45,000 for concrete or gunite. But, custom designs can run prices much higher.