What is the length of half a circle called?

A square has sides which are each 30 inches how many inches is the length of the diagonal? What is the rate of change of position at a specific point in time? What three dimensional shape can be made with 6 squares? Is work a noncount noun? How many significant digits are in this number 39000? How many miles would you have to travel to go from Norway to the Winter Games? What is the name for the number that is being divided in division problem? What do the five sides of the pentagon represent? What can 3101 be divided by? A caamel travels 500 meters in five minutes What is its speed? What is the sq. root of 58? Who wrote the book of job in the kjv bible? When should you write 7.5 instead of 7.50 and vice versa? What set of seven numbers have the same mean median and mode? What is two yard sticks? How many leters are in 5 gallons? What year would i be born in if i was 11 now? When in a day and night is the length 12 hours exactly? How do you get 100 using 1 to 9 only once? What is four and five ninths as an improper fraction?