The largest circular shape my piece of string can form has a diameter of 8 cm long. How long is the diameter of the largest circular shape that half my piece of string can form?

Technicians have installed a center pivot, circular irrigator for a farm that covers 25 acres. a.) how long is the irrigation boom (in feet) from the center pivot to its farthest extent? b.) if the irrigation boom makes 4 full revolutions in a day, how many miles does the end of the boom travel in 5 days?