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数学 高校生

解説お願いします。数Cベクトルです。 (1)の問題で、参考書の方の解説は理解しているのですが、私の解答の間違いが分かりません。 どこが間違えているのか教えていただきたいです。 よろしくお願いします。

思考プロセス 例題 32 三角形の形状・心・心との内 次の等式が成り立つとき, △ABCはどのような形の三角形か。 (1) AB AC = |AB|2| . (2) AB・BC=BC・CA « ReAction 三角形の形状は、辺の長さの関係を調べよ IIB例題 77 ★★★☆ 目標の言い換え △ABCの形状は ? (UE) 75 (ア) A (イ) HLA 長さの等しい辺, 直角となる頂点を考える。 これまで ベクトルの場合 例 (ア) AB AC (二等辺三角形) |AB|=|AC| BOC (イ) BC2=AB2 + AC2 ABAC = 0 B CO nod (A=90°直角三角形) A (2) [左辺・・・ ∠B をはさむ2ベクトル ∠Bと∠Cについて対等 ... [右辺 ∠Cをはさむ2ベクトル > AB と AC の対等性を予想し,始点をAにそろえる。 B C& AO 解 (1) AB·AC = |AB|より 2 AB・AC-ABAB = 0 AB-AB-AB (80+70) AB・(AC-AB) = 0 A AO) よって ABBC = 0 AB = 0, BC ≠ 0 であるから B AB 1 BC 180+800 したがって, △ABC は ∠B=90°の直角三角形 80 AO (別解 + a+bto 単に「直角三角形」 だけ では不十分である。 与式は AB 0 であるから JAB||AC|cosA=|ABC- |AC|cosA= |ABO これが成り立つのは,∠B=90°のときであるから, △ABC は ∠B=90°の直角三角形 Aから IACIAO |AB| + B C |BC| = |CB| ≠ 0 より |BA | cosb1 = |CA|cosin (別解) 与式より BA・BC=CB・CA |BA||BC|cosb1 = |CB||CA | cosbz めに、

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英語 高校生

下から15行目のthrow whichのthrow とはなんですか?

y II Day 12 15 5 Negro Leagues Baseball was a collection of major and minor-league baseball leagues that were the first to showcase black team sports on intertwined with the African American and American experience not only a national scale. Launched in 1895, the leagues, as with jazz, became as a cultural element, but as a lucrative business endeavor. team The leagues were not under central management, and schedules and composition League, were changeable from season to season. Appearance and disappearance of leagues was common: the National Colored Baseball for instance, collapsed after only two weeks of operations. Latins, especially Cubans, were also a significant presence on teams. In these ways, the Negro Leagues were quite similar to their white counterparts which would eventually consolidate into Major League Baseball. Blacks near the beginning of the 20th century had only a fraction of whites' purchasing power, so the emergence of the Negro Leagues might have seemed unlikely. However, the Negro Leagues had two main draws that accounted for its business success. The first was a deep reserve of athletic talent. After blacks were formally excluded from white leagues in the 1880s, the Negro Leagues were the sole organization through which black players could work professionally. The quality of Negro Leagues 20 players was high, and substantiated through exhibition matches between Negro Leagues and Major League teams: over the years, both had their fair share of wins and losses in these matches. Another reason for the success of the Negro Leagues was an increasingly affluent black fan base. Driven by American industrialization, blacks were concentrating in major cities such as New York City, Chicago, and Atlanta. Usually barred by custom-and in the South by law-from attending many white entertainment outlets, blacks turned to Negro Leagues games. As a result of these factors, by the 20th century the Negro Leagues were earning a combined millions of dollars. This profitability ended with the desegregation of Major League Baseball. Black fans began attending Major League games, starving the Negro Leagues of its core revenue source. By 1951, the Negro Leagues had ended, although a succession of black star athletes in the Major League had begun.

未解決 回答数: 1