有一个美国数学题不懂,
问题描述：
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.
答
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.