Grade

Type of questions

Mathematics Senior High

こういうベクトルの問題で、よくこれらのベクトルは0ベクトルではないとか平行ではないとかわざわざ書いてありますが、これを書かなかった場合は減点となりますか?

OC) △ABCの重心をG, 外接円の中心を0とするとき,次のことを示せ。 (1) OA+OR+OCOH である点Hをとると, Hは△ABCの垂心である。 (2) (1) の点Hに対して, 3点 0, G, H は一直線上にあり GH=2OG [類 山梨大 〕 基本 25 基本 71. 指針 (1) 三角形の垂心とは, 三角形の各頂点から対辺またはその延長に下ろした垂線の交 点である。 解答 AH ¥0, BC = 0, BH = 0, CA ¥0 のとき A AHLBC, BHLCA ⇒ AH•BC=0, BH-CA=0 であるから 内積を利用 して A [(内積) = 0] を計算により示す。 Oは△ABCの外心であるから [OA|=|OB|=|OC|も利用。 CHART 線分の垂直(内積) = 0 を利用 (1) ∠A=90°, ∠B=90° としてよ い。 このとき, 外心 0 は辺BC, CA上にはない。 (1) OH=OA+OB+OCから AH-OH-OA=OB+OC B ゆえに AH・BC ...... =(OB+OČ)・(OC-OB) |=|OC|-|OB|= 0 同様にして BH-CA=(OA+OC).(OA-OC) =|OA|-|OC|=0 A OG H C 練習 右の図のように,△ABC の外側に 31 また, ① から AH=OB+OC0, BH=OA+OC≠0 よって, AH≠0, BC ¥0, BH = 0, CA +0 であるから AH IBC, BHICA Oaf すなわち AH⊥BC, BHICA したがって, 点Hは△ABCの垂心である。 (2) OG= OA+OB+OC 3 ゆえに GH = OH-OG = 2OG ETUS! よって, 3点 0, G, Hは一直線上にあり GH=2OG 直角三角形のときは ∠C=90° とする。 D+00A=0B=OC (数学A) このとき,外心は辺AB 上にある (辺ABの中 点)。 p+AD ■BC=OC-OB (分割) △ABCの外心0→ AP=AB, AQ=AC, ZPAB=ZQAC=90° 0 となるように 2点P, Qをとる。 更に、四角形 AQRP が平行四辺形になるように点Rをと ると ARI を証明する = 1/30から OH =3OG (1) から A GAZARD 晶検討 外心, 重心,垂心を通る直 線 (この例題の直線 OGH) を オイラー線と いう。ただし、正三角形 は除く。 OA+OB+OC=OH ORSAN P 00+ HOSI SE E

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English Senior High

教えて下さると嬉しいです( •̥-•̥ )

A. Circle the correct answer for each question. likely to be jealous of someone. 1. You are more 2. Which do many people decorate at Christmas time? 3. Which are people more accustomed to? a. rich a. a feast b. a tree a. spending money b. receiving awards a. an empire b. a rifle a. an insect b. water a. help it b. ruin it 6. What would profit do for a business? a. excited b. confused 7. Which would people rather be? a. a contract b. a feast 8. Which would you invite friends to share with you? a. a recruit b. a contract 9. Which would you sign? a. being punished b. getting a reward 10. Which would few people enjoy? B. Complete the paragraph with items from the box. Two items are extra. Which of these is a weapon? 4. 5. Which of these flows? discovered resembled establishing rights faced status by Roy's s grief the rest of Many people change countries during their life, but one man has (1) (2) son and (10) heir took over This surprised people in the UK, who believed they had the (5) . Bates and (6) to leave the platform. However, Roy (8). in the sea to contain (3) that would be used to fight off invaders. After the war, the soldiers left these platforms and they were forgotten - until 1967. In that year, a British man, Roy Bates, one of the platforms and announced he had started his own country, (4) called Sealand. b. poor himself by his own country. During World War II, the UK built a number of artificial platforms made a name for weapons the people on the island (his family), (7) In 1968, a court decided that the UK had no power over Sealand. Just like other places with the that the platform was in international waters. to the platform. orders of a country, Sealand, has its own stamps, coins, and passports. It is controlled 'Prince' Michael, and is home to a large Internet business. 11 15 69

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