$ 100- 25cos (20) = 76.5076 $ Force in member ob. We divide the tributory of 75 N by this to get the cos(b-a) 75/ 76.5076 = 0.98029 Arccos (0.98029)= 11.3934 This added to 20 is angle beta. Beta = 20 + 11.3934 = 31.3934 And Omega = 180- 31.3934= 148.606