Answer: 60 feet long!
Explanation:
Okay so draw a square and add 60 to each side. Then draw a diagonal line! what is half of 60? 30 so that diagonal line is 30! now do a2 + b2 = c2!
3600 + b2 = 900!
Now Subtract 3,600 - 900 and you will get 2,700 for the area of b but that's not all now you have to square it 59.961
Now I round to the tenths so the answer would be 60!
I haven't done this in a VERY long time! So Sorry if it's wrong!
Hope this helps!