OM=18, so OQ=QM=18/2=9. Given QU=8 from figure OQU is a right angled triangle , so OU^2=OQ^2 + QU^2 OU^2 = 9*9 + 8*8 = 81+72=153; OU=sqrt(153) = 12.37 =13(approx); From given statements of congruent NT and OU will also be congruent or identical. So, NT=OU=13