Question

a boom 4.7 meters,10000 kg, 20 degree angle, find torqe on the pivot

i fond force=10000x9.81= 98100 N
perpindiclar force = 33552 N
torqe = 4.7x33552 = 167695 Nm

i am told this is wrong

Answer 1

toque = 98,100 * 4.7 * cos 20 = 433,264 N m

I think you used sin and not cos
and you have a typo anyway, should be 157,695 N m

Answer 2

Your sin assumption would be correct if your 20 deg boom angle is from vertical, but usually you measure from horizontal.