f.3 maths 三角比的應用 2b

a)CD/BC=sin DBC
CD=BC sin DBC=4 sin 65=3.63 km//

b)AB和C延長的交點為C'
C'C=DB=CB cos DBC=4 cos 65=1.69 km
AC'=AB+BC'=4+DC=4+3.63=7.63 km
tan CAC'=C'C/AC'=1.69/7.63 CAC'=12.49
so ans is N(90-12.49)E=N77.51E//

AC^2=C'C^2+C'A^2
AC^2=1.69^2+7.63^2
AC=7.81 km //

2007-05-09 20:32:03 補充：
你冇比answer我....錦我想correct都唔得la

I just wanna say I got the same answer as the above person. I think you should first double check your answer and READ THROUGH THE LINE AND SEE WHETHER IT IS MAKE SENSE TO YOU. There are possible that your answer is wrong. We are not here to DO your homework for you and you just copy it as your OWN assignment, we are here to HELP OUT.

I am not here to be mean, but you should definitely THINK with YOUR BRAIN, not WAITING TO BE FEED!