…………………………………………………………最新精品资料推荐…………………………………………………… 六年级相关公式总结 圆： 1、圆的周长＝直径×π＝半径×π×2 （字母表示：C＝πd＝2πr） 半径（r）＝圆的周长÷2π＝C/2π 直径（d）＝圆的周长÷π＝C/π 2、圆的面积＝半径×半径×π＝πr² 圆柱： 1、侧面积＝底面周长×高 （字母表示S侧＝πdh＝2πrh） 2、表面积＝侧面积＋底面积×2 （字母表示：S表＝S侧＋2S底＝2πrh＋2πr²＝πdh＋2πr²） 3、体积＝底面积×高 （字母表示：V柱＝S底h＝πr²h） 底面积＝体积÷高 高＝体积÷底面积 圆锥： 体积＝底面积×高×⅓ （字母表示：V锥＝⅓S底h＝⅓πr²h） 圆锥的底面积＝圆锥的体积×3÷高 圆锥的高＝圆锥的体积×3÷底面积 比例尺： 1、 图上距离：实际距离＝比例尺 …………………………………………………………最新精品资料推荐……………………………………………………1 …………………………………………………………最新精品资料推荐…………………………………………………… 2、 实际距离＝图上距离÷比例尺 3、图上距离＝实际距离×比例尺 正比例：y/x＝k（k一定） 1、 正方形的周长与边长。（C/a=4） 2、 高一定，平行四边形的面积与底。（S/a＝h） 3、 底一定，平行四边形的面积与高。（S/h＝a） 4、 高一定，三角形的面积与底。（S/a＝½h） 5、 底一定，三角形的面积与高。（S/h＝½a） 6、 圆的周长与半径。（C/r＝2π） 7、 圆的周长与直径。（C/d＝π） 8、 圆柱的底面积一定，体积与高。（V/h＝S） 9、 圆柱的高一定，体积与底面积。（V/S＝h） 10、 圆锥的底面积一定，体积与高。（V/h＝⅓S） 11、 圆锥的高一定，体积与底面积。（V/S＝⅓h） 12、 比例尺一定，图上距离与实际距离。 13、 实际距离一定，图上距离与比例尺。 反比例：xy＝k（k一定） 1、 长方形面积一定，长和宽。（ab=S） 2、 平行四边形面积一定，底与高。（ah＝S） 3、 三角形面积一定，底与高。（ah＝2S） 4、 圆柱的体积一定，底面积和高。（Sh＝V） …………………………………………………………最新精品资料推荐……………………………………………………2 …………………………………………………………最新精品资料推荐…………………………………………………… 5、 圆锥的体积一定，底面积和高。（Sh＝3V） 图上距离一定，实际距离与比例尺。 Unit 2 Space Invaders Richard Stengel At my bank the other day, I was standing in a line snaking around some tired velvet ropes when a man in a sweat-suit started inching toward me in his eagerness to deposit his Social Security check. As he did so, I minutely advanced toward the woman reading the Wall Street Journal in front of me, who, in mild annoyance, began to sidle up to the man scribbling a check in front of her, who absentmindedly shuffled toward the white-haired lady ahead of him, until we were all hugger-mugger against each other, the original lazy line having collapsed in on itself like a Slinky. I estimate that my personal space extends eighteen inches in front of my face, one foot to each side, and about ten inches in back — though it is nearly impossible to measure exactly how far behind you someone is standing. The phrase "personal space" has a quaint, seventies ring to it ("You're invading my space, man"), but it is one of those gratifying expressions that are intuitively understood by all human beings. Like the twelve-mile limit around our national shores, personal space is our individual border beyond which no stranger can penetrate without making us uneasy. Lately, I've found that my personal space is being invaded more than ever before. In elevators, people are wedging themselves in just before the doors close; on the street, pedestrians are zigzagging through the human traffic, jostling others, refusing to give way; on the subway, riders are no longer taking pains to carve out little zones of space between themselves and fellow-passengers; in lines at airports, people are pressing forward like fidgety taxis at red lights. At first, I attributed this tendency to the "population explosion" and the relentless Malthusian logic that if twice as many people inhabit the planet now as did twenty years ago, each of us has half as much space. Recently, I've wondered if it's the season: T-shirt weather can make proximity more alluring (or much, much less). Or perhaps the proliferation of coffee bars in Manhattan — the number seems to double every three months — is infusing so much caffeine into the already jangling locals that people can no longer keep to themselves. Personal space is mostly a public matter; we allow all kinds of invasions of personal space in private. (Humanity wouldn't exist without them.) The logistics of it vary according to geography. People who live in Calcutta have less personal space than folks in Colorado. "Don't tread on me" could have been coined only by someone with a spread. I would wager that people in the Northern Hemisphere have roomier conceptions of personal space than those in the Southern. To an Englishman, a handshake can seem like trespassing, whereas to a Brazilian, anything less than a hug may come across as chilliness. 6、 …………………………………………………………最新精品资料推荐……………………………………………………3 本文来源：https://www.wddqw.com/doc/2c255837ecfdc8d376eeaeaad1f34693daef1053.html