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阅读短文，然后根据内容回答所提问题。A trip to spaceby Jerry10 October, 2017I’m so happy! Tomorrow I’ll be one of the first students to travel into space. The spaceship will leave the Earth at 9 a.m. It’ll take us to the Moon. I can’t wait.The Moon is around 380,000 kilometers from the Earth, so it’ll take us about four days to get there. There’s no gravity in space, so we’ll all be able to float around in the spaceship. We’ll have to tie ourselves to our beds so that we won’t float away in our sleep! Without gravity, our bodies may get weak, so we’ll have 已知一个圆锥的底面半径为2，高为4，则这个圆锥的侧面积为    ．