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如图,直角三角形ABC中,∠ACB=90°,BC=3,AC=6,E为BC延长线上一点,且EC= 25
4
,过点E作EF⊥AB交AB于F,将△ABC沿AB翻折,得到△ABD,将△ABD绕点B旋转,在旋转过程中,记旋转中△ABD为△A′B′D′.设直线A′D′与射线EF交于点M,与射线EB交于点N,当△EMN是以∠MEN为底角的等腰三角形时,EN=____

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13\u6216 374 +3 5

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    Driverless technology will soon enter another major global industry: shipping. Several companies recently announced plans to start self-sailing ships to improve safety and efficiency(效率).

    One of them is Norwegian chemical company Yara International. Yara has designed to build an autonomous ship expected to start next year. The ship is fully electric to reduce air pollution. It is designed to carry containers normally transported by truck. This means the ship will also improve road safety by replacing about 40,000 truck trips a year.

    Yara plans to operate the ships by remote control beginning sometime next year. By 2020, the ships should be loading and sailing themselves. Another company focusing on self-sailing ships is the world's largest mining company, Australia's BHP Billiton. The company's Vice President of Freight, Rashpal Bhatti, recently spoke about the technology. He said, “I believe automation(自动化)will be one of the biggest changes for shipping in the future.” Autonomous ships offer important chances to improve safety and provide better efficiency results to the marine supply chain. He added that self-sailing ships could become a reality within the next decade.

    Rolls-Royce, the British automobile and engine manufacturer, is also developing unmanned shipping technologies. Oskar Levander is the company's head of marine operations. He told a conference last year, “This is happening. It's not if, it's when.” Several shipping companies have invested hundreds of millions of dollars to develop self-sailing ships expected to be used by 2025. These ships will be equipped with technology to collect weather and sea data. They will then use the data to plan out the safest, shortest and most fuel-efficient route.