12. A helicopter is observed at the same time by two observers on the "' ground who are 3.5 miles apart as shown in the diagram. If they _ , ,. 1127': report angles of elevation of 20 and 30", what is the helicopter's /,.-""," altitude, rounded to the nearest hundredth of a mile? 4' \"26);" \"'36; A. 5.97 miles B. 3.45 miles *4 """"""""""" 3.5 miles C. 10.08miles D. 6.89 miles