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数学 高校生

なぜAB+BC+CAは ①次の丸で囲ったような式になるのですか? ②BCは2ではないのですか? √2かける√2ではないのですか?

基本例題 168 円錐に内接する球の体積・表面積 図のように, 高さ 4,底面の半径√2の円錐が球Oと側面 で接し、底面の中心Mでも接している。 (1) 円錐の母線の長さを求めよ。 (2) 球Oの半径を求めよ。 (3) 球Oの体積V と表面積Sを求めよ。 指針 円錐の頂点Aと底面の円の中心 M を通る平面で円錐を切った切り口の 図形 (右図の二等辺三角形ABC) について考える。 (1) 円錐の母線は、 右の図の辺AB である。 (2) (球の半径)=(△ABCの内接円の半径) 1801 4 (3)(2) の結果と公式 V=13πr", S=4zr2 を利用。 CHART 空間図形の問題 平面で切る(断面図の利用) 解答 円錐の頂点をAとすると, A と点M を通る 平面で円錐を切ったときの切り口の図形は, 図のようになる。 (1) 母線の長さは √BM2+ AM2=√(√2)^2+4°=3√2 (2) 球Oの半径をrとすると △ABC=11 (AB+BC+CA) M = 2/(2√2+3√2.2) =4√2r △ABC=121・2√2・4=4√2 であるから したがって 2 (3) (2)から 4√2r=4√2 r=1 •1³= S=412=4π 基本 161 A TC ABC = √2+√²2² = 2 2²/₁24=1 C 三平方の定理 ではないのか BMC \AABC=AOAB A M + △OBC+ △OCA ■△ABC=1/2BCAM Lokator 4 3 <S=4πr2 <V= p. 250 例題 161 (3) と同じ 要領。 πr³ 259 Dus 4章 19 三角比と図形の計量

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英語 中学生

解答解説がなく、困っています。 赤丸(大問②⑤⑥、大問④の小問2)のところについて、回答、解説教えていただきたいです🙇‍♀️

4 次の英文は、英語の授業の課題として, 中学3年生の研翔(Kento)が書いた英文です。これを読 んで、あとの問いに答えなさい。 I'm going to write about my experience. Ahn the ル ついて書皿 My father started living in London five years ago. When I 母は5年間ロンドンに住んでいた。 was eleven, my mother and I went there to live with my father. さいの A 1242 = 12 115 We lived in London for three years. Yan x Last month, my family came back to Japan. 先月 121. We were living with my father in London, so I was ti ) at 私たちは父と住んでいた。 だから、暴れる悲しかった first. But I worried about school because I couldn't speak English well. There were a lot of students from other countries at school in London. Some of them spoke English very well, and others didn't. But they always looked happy when they were talking Little by little I learned English through talking with the other 10 students. I started to feel that speaking English was not a big problem. together. B One day, an American student came to talk to me. He said, "Hi. My name is Kent Jones. Your name is the same as mine, right?" "Yes," I said, “Our names are almost the same. We use kanji.” I wrote my name in kanji. I said, "This is my name. means studying, and 'to' means flying." Kent said, "Wow, that's a cool name." and I became good friends and often visited each other's families. 'Ken' Kent 15 C I Kent's father often took me to nice spots in and around London. found that Kent ew a lot about the history of London. He taught me a lot about the culture there. I really enjoyed talking with his family. However, there was a problem. Kent's family liked Japan and wanted to know more 20 about it. When they asked me about Japanese culture such as food or history, D I was sad. I realized I didn't know many things about my country. realized I had to learn more about Japanese culture. After I came back to Japan, I continued to talk with Kent on the internet. My English is getting better, but I should learn more about my own country. I'm going to study hard 25 about Japanese history and talk to Kent about it. I hope we will meet in Japan someday. (2) () London F month A at first 最初は American アメリカ人の the same as ~ ~と同じ each other おたがい take ~を連れていく spot taught teach however しかしながら own 自分自身の someday いつか internet インターネット I also little by little 少しずつ through ~を通して almost ほとんど fly knew know(~だとわかっている)の過去形 ask ~にたずねる realize 〜だと実感する

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