Hi
I'm new to the forum so I hope I'm posting in the correct place.

Anyway, there's a question that I'm really stuck on, I know it's probably simple but I can't seem to see where I'm going wrong. If anyone could help with how to work it out, I would be so grateful. Here it is:

In the following diagram, AB=8.5m is the perpendicular height of a pole, and CD=6.9m is the perpendicular height of a second pole. The angle CDB is 100º. Calculate:
a) the distance AC between the base of the poles. (2d.p.)
b) the length of BD, the distance between the tops of the poles. (2d.p.)

sketch an auxiliary line ED parallel to AC ... $m\angle{BDE} = 10^\circ$
$\Delta BDE$ is a right triangle ... you have a side length (BE) and an angle.