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Mathematics Senior High

青チャートのAです かっこ1で証明に使わない角についてわざわz言及しているのはなぜですか

87 基本例題 接弦定理の逆の利用 00000 10の外部に接線 PA, PB を引く。 点Bを通り, PAと平行 SCOUT な直線が円0と再び交わる点をCとする。 <PAB=a とするとき, ∠BACをaを用いて表せ。 直線 AC は △PAB の外接円の接線であることを証明せよ。 指針 (1) 円の外部の1点からその円に引いた2本の接線の長さは等しいことや, 接弦定理, 平行線の同位角・錯角に注目して,∠PAB に等しい角をいくつか見つける。 (2) 接線であることの証明に、次の接弦定理の逆を利用する。 0,348 TERA 円 0 の弧 AB と半直線 AT が直線 AB に関して同じ側にあって ∠ACB=∠BAT ならば,直線ATは点Aで円0に接する (1) の結果を利用して,∠APB=∠BAC を示す。 解答 (1) PA=PBであるから ∠PAB=∠PBA=a また, PA//BC であるから ∠ABC=∠PAB=α 更に ∠ACB=∠PAB=α よって, △ABCにおいて ∠BAC=180°−2a ...... P おいて、円の CHART》 接線であることの証明 接弦定理の逆が有効 (19) A B89 使わない DETERA ∠APB=180°-2a 0円 13 p.436 基本事項 ② ...... A HA3 | 接線の長さの相等。 a NGAPDATA C onit SA SEN 09:A ART SI (2) AAPBにおいて 1⑩② から ∠APB=∠BAC THIAPATIA したがって,直線 AC は △PAB の外接円の接線である。 A4 接弦定理の逆 B 439 T > 平行線の錯角は等しい 接弦定理 PROL PA- とし、その手をとすると、名は てみよし、これから △PAB は二等辺三角形。 79-84-A4 A 章 144 円と直線、2つの円の位置関係 <DO & FR>

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English Senior High

英語リーディングの共通テスト大門3のB 4つの選択肢を並べるような問題が苦手で、対策問題集を解いている時にいつもどこかしら間違えてしまいます。時間制限を決めつつ、正しい答えを選ぶことがとても難しい状態です。 どのように考えれば良いでしょうか。 また模試などでは、時間と正確... Read More

B You enjoy outdoor sports and have found an interesting story in a mountain climbing magazine. Attempting the Three Peaks Challenge By John Highland Last September, a team of 12 of us, 10 climbers and two minibus drivers, participated in the Three Peaks Challenge, which is well known for its difficulty among climbers in Britain. The goal is to climb the highest mountain in Scotland (Ben Nevis), in England (Scafell Pike), and in Wales (Snowdon) within 24 hours, including approximately 10 hours of driving between the mountains. To prepare for this, we trained on and off for several months and planned the route carefully. Our challenge would start at the foot of Ben Nevis and finish at the foot of Snowdon. Ben Nevis (▲1344 m) Scafell Pike (▲977 m) Snowdon (▲1085 m) We began our first climb at six o'clock on a beautiful autumn morning. Thanks to our training, we reached the summit in under three hours. On the way down, however, I realised I had dropped my phone. Fortunately, I found it with the help of the team, but we lost 15 minutes. We reached our next destination, Scafell Pike, early that evening. After six hours of rest in the minibus, we started our second climb full of energy. As it got darker, though, we had to slow down. It took four-and-a-half hours to complete Scafell Pike. Again, it took longer than planned, and time was running out. However, because the traffic was light, we were right on schedule when we started our final climb. Now we felt more confident we could complete the challenge within the time limit. Unfortunately, soon after we started the final climb, it began to rain heavily and we had to slow down again. It was slippery and very difficult to see ahead. At 4.30 am, we realised that we could no longer finish in 24 hours. - 16- (2110-16)

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