Round answer to two significant digits

A telephone pole 40 feet high is situated on an 13° (H) slope from the horizontal. The measure of angle CAB is 21°. Find the length of the guy wire AC.

see this one, almost identical http://www.jiskha.com/display.cgi?id=1392629453http://www.jiskha.com/display.cgi?id=1392629453