AB = 85m what is the length of CD

CD = x

BC = y

AB = 85

BD = BC+CD = y+x

tan (angle) = opposite/adjacent

tan (28) = BC/AB

tan (28) = y/85

85*tan (28) = y

y = 85*tan (28)

y = 45.1953016912257

tan (angle) = opposite/adjacent

tan (31) = BD/AB

tan (31) = (y+x) / 85

tan (31) = (45.1953016912257+x) / 85

85*tan (31) = 45.1953016912257+x

51.0731526173427 = 45.1953016912257+x

51.0731526173427-45.1953016912257 = 45.1953016912257+x-45.1953016912257

5.877850926117 = x

x = 5.877850926117

So CD is roughly 5.877850926117 meters