Can someone help me please

Which statement justifies why angle ebc measures 90?

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83

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?