Проведем сечение I-I:
ΣM1лев = -U4-5·h + P·0,5·d – P·0,5·d – P·d = 0
U4-5 = -P·d/h = -12,5·3,5/3,2 = -13,67 кН
ΣM5лев = O1-2·h + RA·d - P·0,5·d – P·1,5·d – P·2d = 0
O1-2 = (4·P·d – RA·d)/h = -20,51 кН
ΣYлев = RA – 3·P – D3-5·cosα = 0 α = arctg(d/h) = 47,31°
D3-5 = (RA – 3·P)/cosα = 46,31 кН