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数学 高校生

数2の直線の方程式です。 y=ax+bの式に代入して連立方程式にしても解けると思うんですが、なんでこんな公式があるんですか?!

122 基本 例題 70 直線の方程式 次の2点を通る直線の方程式を求めよ。 (1) (3,-2), (4, 1) (3) (-2, 3), (-2,-5) CHART & SOLUTION 00000 (2) (4, 0), (0, 3) (4) (-3, 2), (1, 2) p.120 基本事項 異なる2点(x1, 1), (X2, yz) を通る直線の方程式 [1] X1 X2 のとき [2] x1=x2 のとき x=x1 [解 Ante 合 (1) y-(-2)=1-(-2) 2(x1) x2-x1 交 4-3 (x-3) / (1) すなわち y+2=3(x-3) よって y=3x-11 3 1 310 (2) y-0-3-0 (x-4) 0 4 x Ea 3 よって y=-2x+3 (3) x座標がともに-2であるから x=-2 (4) y座標がともに2であるから y=2 Stixol YA [int 公式 [1] yy=12-11(x-x) の X2-X1 両辺に X2-x1 を掛けて (y2-y₁)(x-x1) -(x-x1)(y-1)=0 x= x2 とすると (y2-y₁)(x-x1)=0 yyであるから x=x (公式 [2]) (3)3 (4) 2 -2 ! よって, * は公式 [1] [2] -3 0 1 x をまとめたものである。 (p.120 基本事項 1③) -5 POINT a≠0, b=0 のとき, 2点 (α, 0), (0, 6) を通る直線 lの方程式は b-0 y-0= (xa) すなわち + 1/2=1 0-a a b ya このとき, αを直線lのx切片, bを直線lの切片という。 (2) は,これを公式として用いてもよい。 0 a b 全で ための PRACTICE 70° 次の直線の方程式を求めよ。 (1) 点 (35) 通り,傾きが√3 (3)2点 (5,1) (3,2)を通る (5)2点(-3,1) (-3, -3) を通る Ja,0)s(s) (2)2点 (5-3), (-7, 3) を通る (4) 切片が4, y切片が2z (6)2点 (1-2) (-5-2) を通る x

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数学 高校生

(2)の問題が解説見てもわからなくて、教えてほしいです🙇‍♀️

(1)正四面体に外接す 2) 正四面体に内接する球の半径をα を用いて表せ。 CHART & SOLUTION (1)基本例題138と同様に,頂点Aから底面△BCDに垂線 AH を下ろす。 外接する球の中心を0とすると, 類 神戸女 ◎基本 ( 重要例 1辺の を, A (1)線 (2) S CHAR AD=C 2次関 (1) D OA=OB=OC=OD(=R) よって、直角三角形OBH に着目して考える。 である。また, 直線AH 上の点Pに対して, PB=PC=PD であるから, 0は直線AH 上にある。 B (2) 内接する球の中心を I とすると, Iから正四面体の各面に 下ろした垂線の長さは等しい。 正四面体をⅠを頂点とする 4つの合同な四面体に分けると, 体積は 四面体 IABC, A 正四面体=4×(四面体 IBCD) IACD, IABD, IBCD これから, 半径を求める。 B (例題 136 で三角形の内接円の半径を求めるとき,三角形を つの三角形に分け、面積を利用したのと同様。) HASE HBAC khe (1) 頂点Aから底面 △BCD に垂線 AH を下ろし、外接する 球の中心を0とすると, 0 は線分AH上にあり ←AH=6 3 -a, BH= OA=OB=R は基本例題 138 (1) の ゆえに OH=AH-OA= √6 03 果を用いた。 a-R A 3 よって △OBHで三平方の定理から 2 BH2+OH2=OB2 (3)²+(√a-R)²=R² すなわち - 2√6 3 -αR=0 ゆえに R=- 3 √6 a= 2√6 4 a B (2) 内接する球の中心をIとする。 4つの四面体 IABC, IACD, IABD, IBCD は合同であるから V=12 V=4×(四面体IBCDの体積)=4 (13△BCD・ 1.13 = 4.1. √3a²• r = √3a²r =4• 123から 3 √2 = 12 √3 a²r よって r=- a 12 PRACTICE も (2) S 解答 AD= (1) (2 V=12 12 138(2)の針用 -αは基本例題 F

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TOEIC・英語 大学生・専門学校生・社会人

青くしてある文の文構造と訳し方を教えていただきたいです🙇‍♀️ また、mainstream America の語順に違和感を感じていて、(American mainstream とした方が正しくない?と思ってしまいます、、)それも解説いただきたいです。

Neil Hello. This is 6 Minute English from BBC Learning English. I'm Neil. Georgie And I'm Georgie. Neil If I told you I'd been for a walk to see Big Ben and Buckingham Palace, you'd know straight away I was in London. Georgie But what if my walk went past cafes selling mozzarella and ricotta where I smelled freshly made cannolis and focaccia... Where would I be then? Neil Focaccia and mozzarella... you'd be in Italy, right? Georgie Yes, Italy, or 'Little Italy' to be exact - the neighbourhood in some cities where Italian communities settled and made their home. Neil These Italian arrivals opened shops and cafes selling food to their own communities. Soon dishes like spaghetti and meatballs attracted the attention of local people, and gradually Italian food became famous around the world. In this programme, we'll be taking a walk through two Little Italys, one in Argentina, the other in New York, and, as usual, we'll be learning some useful new vocabulary as well. But before that, I have a question for you, Georgie. According to a recent YouGov poll, which Italian food is most popular with British diners? Is it: a) pizza? b) lasagne? or c) garlic bread? Georgie I think it must be pizza. Neil Okay, Georgie, I'll reveal the answer at the end of the programme. One country Italians moved to was Argentina. In 1898, Giuseppe Banchero arrived in the neighbourhood of La Boca, the Little Italy of Buenos Aires, where many Italian immigrants started restaurants. Here, Hugo Banchero, grandson of Giuseppe, tells his story to Veronica Smink, reporter for BBC World Service programme, The Food Chain: Hugo Banchero Well, my grandfather came from Italy, from Genoa, from Liguria. He was born in the centre of Genoa and arrived here in 1898 at the age of seven and a half, and this pizzeria where we are was founded on March 28, 1972. We have been here for 91 years. Veronica Smink So what culinary traditions did they bring with them? Hugo Banchero Well, our culinary tradition is pizza, and we incorporated the faina from Genoa, which is a pizza with chickpea flour... Georgie In 1898, Giuseppe founded his pizzeria - a restaurant selling pizza. When a business is founded, it's established someone starts it, or sets it up. Neil Giuseppe brought the culinary traditions from his home in Liguria in northern Italy, including regional pizzas like faina and fugazzetta. The adjective culinary describes anything connected with cooking. Georgie But probably the best-known Little Italy in the world is an area of Manhattan's Lower East side in New York. Ninety percent of Italian immigrants who arrived in the US at the turn of the century came through this neighbourhood. Neil De Palos, one of the original shops selling Italian food in Little Italy, has been serving customers for 113 years. Here, Lou De Palo, co-owner and great-grandson of the original owner, Salvino, explains more about his family history to BBC World Service programme, The Food Chain: Lou De Palo 1925... when my grandmother, Concetta, and my grandfather, Luigi, got married, they open their own shop... it's the shop we continue today being the fourth generation working alongside my sister, Maria, my brother, Sal, and our children, the fifth generation. Our business has expanded; expanded to present the full food culture of the 20 regions of Italy. Little Italy is the stepping stone of the Italian immigrant. This is where many of the Italians first came through Ellis Island, and then settled here, and then eventually moved into mainstream America throughout the rest of the country. Georgie Lou De Palo is the fourth generation of his family to run the shop, and his children will be the fifth. Phrases like fourth or fifth generation describe the children of people whose parents immigrated to a particular country.

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