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数学 高校生

この軌跡の問題の代入するという考え方がいまいち分からないです。 st、xyの関係式を作って代入するところまではわかるのですが、、、 どうしてどれでstの方程式をxyの方程式に作り替えられるのか分からないです

00000 /p.174 基本事項 ■ 2 重要 113 114 基本例題 110 三角形 2点A(6,0), B(3,3)と円x2+y^2=9上を動く点Qを3つの頂点とする三角形 の重心Pの軌跡を求めよ。 指針 動点Qが円周上を動くにつれて, 重心Pが動く。 このようなものを連動形 (Q 以外の文字で表す。 動してPが動く)ということにする。 連動形の問題では,次の手順で考えるとよい。 ①1 軌跡上の動点P(x, y) に対し、 他の動点Qの座標は,x, 例えば, s, tを使い, Q(s,t) とする。 [②] Qに関する条件を s, tを用いて表す。 ③3 2点PQの関係から,s,tをx,yで表す。 ④ ② ③ の式からst を消去して,x,yの関係式を導く。 なお, 上で用いたs, tを本書ではつなぎの文字とよぶことにする。 CHART 連動形の軌跡 つなぎの文字を消去して、xの関係式を導く P(x,y), Q(s,t) とする。 解答 点Qは円x2+y2 = 9上を動く から s2+12=9 点Pは△ABQ の重心である から x= 6+3+s 3 y= ...... 0+3+t 3 (2) s=3x-9, t=3y-3 よって, 求める軌跡は (s, t) Q₁ ****** -3 3 ②から ①に代入して したがって ゆえに, 点Pは円 ③上にある。 逆に, 円 ③上の任意の点は,条件を満たす。 練習 放物線 y=x2. 10 線 ① 上を動くとき、次の点Q (3, 1) A 0p(x,y)/3 6 X -3 (3x-9)²+(3y-3)²=9 (x-3)^+(y-1)'=1 中心が点 (3,1), 半径が10円 (*) B(3, 3) 注意 上の例題の直線AB:x+y-6=0と円x²+y²=9は共有点 をもたないから、△ABQ を常に作ることができる。 しかし、直 線AB と円が共有点をもつときは,その共有点をRとすると, 図形 ABR は三角形ではなくなるから, そのときの点Pを軌跡 から除外しなければならない。 (3) 点Qの条件。 R の軌跡を求めよ。 点Pの条件。 P Q の関係から,s,t をx, yで表す。 なお, Aは UP {3(x-3)}^+{3(y-1)}^=9 この両辺を9で割って ③ を導く。 (*) 円(x-3)+(y-1)'=1 でもよい。 直線AB Ay 6 3 13 ・①とA(1,2), B(-1,-2), C (4,-1) がある。 点Pが放物 6 C

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英語 高校生

UNITE2.5のreason5の解答を無くしたため教えていただきたいです。 至急よろしくお願いします

occasions at school, most school songs (2) sometimes (3) gal ni owoq low. 22 by famous musicians, but these days, anoijasu school songs themselves. 5 Fill in each blank so that each pair has almost the same meaning. answer the questi CH? the pass China gave Japan two pandas in 1972 as a symbol of friendship. ) ( ) ( (1) Two pandas from China ( 18.0 1972 as a symbol of friendship. CO JounA few villagers saw a gang go into the bank by the back door. (2){ ) ( ) ( kids together. (3) In ancient times, food and water were shared and kids ( C A gang was ) into the bank by the back door. In ancient times, the whole community shared food and water and took care of The law in this country says children under 12 (2) その絵は古い博物館で発見された。 ) ( ) by the whole community. 6616 Americans have known this Japanese song since it came to the U.S. in the 1960s. (4) This Japanese song ( ) ( ) ( ) ( ) Americans since it came to the U.S. in the 1960s. Vocabulary [] [自然] 7 Choose the best option. (1) My father works at a research center for the ( a. reservation b. typhoon c. forecast ) Japan in ) ( MEME UT 6 Put the Japanese into English. (各4点) ni TewanА Sygiene soubor vidsdong a19vh baensqet 916 VIWA (1) この国の法律では, 12歳未満の子供を1人にしてはいけないと定められている。 redog on (3点) Hints on 19lov frilastol ◆ This chain restaurant can be found only in Okinawa. [沖縄だけで見ることができる] 21 1920 19dew (altas709 ◆ This cheese is made at a local farm. [地元の農場で作られる] slup A bak roda alone. 6 (2) (S) ) of rare plants. d. conservation ide om s

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英語 高校生

英単語教えて欲しいです。 間違えてるところあったら教えて欲しいのと、分からないところが沢山あるのでこの文章の中に書かれている単語で右の空欄教えて欲しいです。お願いします。

20 25 20 35 15 STEP 3 DEAR (1年7月改) 回 目標 IGG 登場人物の心情を想像しながら読み進めよう。 次の英文を読んで,あとの問いに答えよ。 取り組み日 A 日 得点 /18 目標時間 17分 tell Sara was annoyed/when her mom told her the news. from Japan/to live with her family//Their two-bedroom apartment/was(already crowded/ with her mom, dad and her.// While her mom was from Japan/Sara (7)/She knew only a few Japanese words. 5 Her mom told her about Sara's Grandpa)//He studied English (in college, but Sara and Grandpa had never spoken (in English.) When she went to Japan every summer, the most. they said to each other was "Ohayo" in Japanese. Grandpa didn't talk much. A month had passed since Grandpa moved in/With the new family member in her home, Sara spent more time alone in her room working on her favorite hobby drawing 10 comic strips./She hardly showed these drawings to anyone.) Her parents thought it was a waste of time. They hoped she would spend more time on her schoolwork.)// Sara had been working for months on a 16-page comic book about a teenage girl with magic powers. She hoped to enter it in a comic book contest the next month but was struggling with how to draw the hero with invisible magic powers// One afternoon, she got so frustrated that she crushed almost all the pages she had drawn and threw them in the wastebasket) She didn't know why but her eyes were full of tears. //Her Her grandfather was moving She grabbed her jacket and went into the living room. Grandpa was reading a book (on the sofa. She said, "Please tell my mom that I went for a walk. Grandpa said. “Itterasshai" to her but she walked out of the room. When she came home, Sara was still upset, but more disappointed. a comic book that she could hand in for the contest. del pr Then she saw her desk. Her drawings were put back on the desk//They were laid flat and attached with small sticky notes all over the pages.// Sara(1-0)Who had gone through her wastebasket? //This was her room.//No one came in without telling her.)// The handwriting on the sticky notes) was really easy to read//She (quickly) realized they were from Grandpa. 'here wouldn't be "Sara, you have a gift for art," the first note said. The second note was longer/"When 30 I was your age. I also wanted to be a comic artist."// The other notes gave to her face."Finally, someone understands my passion I Sara advice on improving her comic strips. Sara felt a smile coming to never imagined Grandpa would ()do that!" She started writing a card to Grandpa "Dear Grandpa /Thank you so much for your kind comments! I want to finish my comic book so I can enter it in the contest next month//Please be my advisor!/Love, Sara"// Grandpa was watching TV with her parents in the living room but looked at Sara/as she walked up to him.// Sara (1-2), so she handed him the card without a word. She wondered if Grandpa 40 would accept it. When he read the card, he smiled but did not say anything, either. Sara quickly went into her room. Her parents were wondering what had just happened. (1) She went straight back to the desk/and started working on her comic book //She only had a month. She couldn't wait to show Grandpa her next draft for more advice. (567W) 内 () ORIGINAL MATERIAL

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