Four identical 2500 kg objects are at the corners of a square with 12 m sides what is the distance between a and d

Please see attached diagram

We have square ABCD

Since ABCD is a square, all lines are of equal length

Therefore, lines AB, BC, CD and AD are 12m in length

If we draw a line from A to D, ACD forms a right angled triangle

The line AD is the hypotenuse of the right angled triangle ACD

Therefore, AC^2 + CD^2 = AD^2 (Pythagoras theorem)

AD^2 = 12^2 + 12^2

AD^2 = 144 + 144

AD^2 = 288

AD = 16.97

Therefore, the distance between A and D is 16.97m

Neptune is the eighth planet from the sun. it was the first planet to get its existence predicted by  mathematical calculations  before it was actually seen through a telescope on sept. 23, 1846. irregularities in the orbit of  uranus  led french astronomer alexis bouvard to suggest that the gravitational pull from another celestial body might be responsible. german astronomer johann galle then relied on subsequent calculations to   spot neptune via telescope. previously, astronomer galileo galilei sketched the planet, but he mistook it for a star due to its slow motion. in accordance with all the other planets seen in the sky, this new world was given a name from greek and roman mythology — neptune, the roman god of the sea.

The answer is d) by requesting advice on science internet sites