某人要測量一座山的高度,他在山底所在的水平面上,選取在同一直線上的
三點(diǎn)進(jìn)行測量。他在A點(diǎn)測得山頂?shù)难鼋鞘?img src="http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823155542760221.gif" style="vertical-align:middle;" />,在B點(diǎn)測得山頂?shù)难鼋鞘?img src="http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823155542775239.gif" style="vertical-align:middle;" />,在C點(diǎn)測得山頂?shù)难鼋鞘?img src="http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823155542869229.gif" style="vertical-align:middle;" />,若
,則這座山的高度為
(結(jié)果用
表示)