在平地上直立一不知高度的扒杆,将缆风绳一端系在扒杆顶上,另一端系在地锚上。现只给一盘卷尺,你能想个办法,既不将杆放倒,也不登高攀杆而测出扒杆的高度吗?设扒杆的高度为(?),取缆风绳中任意一根(以松开该绳时扒杆不倒为度),长度为(?),在缆风绳的C点作标记,松开(?),拉直移到与扒杆重合的位置,在(?)上取一点D,使(?)=(?),用卷尺量出(?)和(?)的长度,根据勾股弦定理,就 Stand upright on a flat ground with a mast not knowing the height. Attach one end of the cable winder to the top of the mast and the other end to the anchor. Now only give a tape measure, can you think of a way to measure the height of the mast without putting it down or climbing it? Set the height of the mast to (?) One (in order to loosen the rope, the mast does not fall down to degrees), the length is (?), mark at point C of the cable wind rope, loosen (?), straighten to move to coincide with the position of the mast, Take a little D on (?), make (?) = (?), measure the length of (?) and (?) with a tape measure, according to the theta theory,