有一个美国数学题不懂,An observer in a lighthouse is 70 ft above the water.He sights two boats in the water directly in front of him.The angle of depression to the nearest boat is 400.The angle of depression to the other boat is 240.What is

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有一个美国数学题不懂,An observer in a lighthouse is 70 ft above the water.He sights two boats in the water directly in front of him.The angle of depression to the nearest boat is 400.The angle of depression to the other boat is 240.What is

有一个美国数学题不懂,An observer in a lighthouse is 70 ft above the water.He sights two boats in the water directly in front of him.The angle of depression to the nearest boat is 400.The angle of depression to the other boat is 240.What is
有一个美国数学题不懂,
An observer in a lighthouse is 70 ft above the water.He sights two boats in the water directly in front of him.The angle of depression to the nearest boat is 400.The angle of depression to the other boat is 240.
What is the distance between the two boats?Round to the nearest foot.
A.107 ft
B.84 ft
C.98 ft
D.91 ft
标准答案是C,但是我觉得不对.我算的是73.80.求指导.

有一个美国数学题不懂,An observer in a lighthouse is 70 ft above the water.He sights two boats in the water directly in front of him.The angle of depression to the nearest boat is 400.The angle of depression to the other boat is 240.What is
那个俯角是40度和24度吧!
70/tan24度-70/tan40度=73.7998226917,我算的和你一样.估计答案错了.

有一个美国数学题不懂,An observer in a lighthouse is 70 ft above the water.He sights two boats in the water directly in front of him.The angle of depression to the nearest boat is 400.The angle of depression to the other boat is 240.What is 有不懂的数学题怎么办? 如果有数学题不懂怎么办? 我有一个数学题不懂,THX!:)化简 (sinβ-cosβ)/(tanβ-1) . 我有一个叫Jane的美国笔友.I have ----- an American pen pal -----Jane. 一个数学题,不懂.3/0.75化简比 一个数学题,有图. 如果有什么不懂的数学题或物理题, 数学题!我不懂. 还是不懂数学题, 数学题不懂做怎么办 我有一个不懂的数学题,一个长方体玻璃缸,底面是周长为60厘米的正方形,现向缸内倒9升水,缸内水深多少厘米? an obsessional neurosis 不懂 同学们排成正方形,方正的最外成共有48人一个数学题,帮我讲讲,我搞不懂求每边有多少人 问一个数学题,有图, 美国国旗中有多少颗星?不懂的请不要乱答 一道数学题画线处不懂 一道高中数学题有些不懂