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数学 高校生

この問題を、自分は次のように考えたのですが、なぜ自分の考えた方ではダメなのでしょうか?

例題 154 三角方程式の解法(和と積の公式利用) ate 254 KOsost のとき,次の方程式を解け。 25 cos 20+cos 30+cos 40=0 2倍角,3倍角の公式を利用し, cos@ の4次方程式にして解くのは計算が大変( 2=30 に着目 して, 第1項と第3項の和を積の形に直すと、第て環、 ■基本 三食 指針 照)。そこで、 20+40 2 (8+A) の共通因数が現れる。 asiné Aaie 三角関数の和やれ rsin ( CHART」 1 2項ずつ組み合わせる 2 共通因数の発見 cos0=x とおくと 別解 cos 40=cos 2·20 本 解答(左辺)= (cos40+cos20)+cos30 T 15 証明 40-20 COS +cos30 - = 2 =2cos'20-1 40+20 =2cos 2 +Aia)3DDai+&n-2(2x°-1}-1 よって,左辺は 2x?-1-3x+4x 日+A+2(2x-1)?-1 =8x*+4x°-6x°-3x =2cos 30cos 0+cos30 (+A)e+(日ate土 =cos 30(2cos0+1) よって,与えられた方程式は cos 30(2cos 0+1)=0 Coa 97 8+A=x(2x+1)(4x°-3) ゆえに,方程式は 1 cos 30=0 またはScos0= 2 S. x(2x+1)(4x-3)=0 +したがって ゆえに 0S0ST から 0S30<3π 200S a00 この範囲で cos 30=0 を解くと 6800-(0 x=0, - 200 すなわち 13 Icos 2? 1 土 2 30=27, 2" A 200g π 3 5 2'2 ( 2~) 0g S A cos 0=0, 土 13 5 ーT 6'2'6 よって 0=- π π 20) 2?」 2 0<0ST の範囲でこれを 0S0ST の範囲で cos0= 解くと 1 を解くと 2 0=x 2 π 3 2 5 6' 2' 3 67 π したがって,求める解は リ= (大研度 2 つ日AA 0=エ 5 6'237, 67 ie +le0 (1) の公

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化学 高校生

【英語ですみません】最後の12番は何を書いたら良いのでしょうか…? Video C の実験では、aqueous solution にlead(ii) nitrate, aqueous solution にPottasium iodide を入れていました。 2KI (aq)... 続きを読む

With lead (I) nitrate solution. This precipitation reaction produces a bright yellow solid. (point values in parentheses) Part 1: 1. Copy the unbalanced reaction below into your lab notebook. Balance the reaction by adding coefficients. (1) KI (aq) Pb(NO,), (aq) KNO, (aq) Pbl, (s) 2. a) Which trial are you assigned? b) Copy the data table below into your notebook. Watch video A (make sure it's the correct trial!) and collect your data. You may need to pause or rewatch the video, it goes quickly. (1.5) Mass of Empty Beaker (g) Mass of Beaker+ solid Pb(NO,)。(g) Volume of 1.0 M KI (aq) (mL) For the following calculations, show all your work for full credit. 3. What mass of solid Pb(N0,), was added to the beaker? (1) 4. If the solid Pb(NO,), was dissolved in 45 mL of water, what is the molarity of the Pb(NO,)。 solution? (2.5) 5. Which compound is the limiting reactant? (4) 6. What mass of lead (II) iodide (PbL,) should be produced? (2) Part 2: 7. Watch video B (make sure it's the correct trial!) to see the complete reaction and collection of the product. Copy the data table below and record your data. (1) Mass of filter paper (g) Mass of filter paper + dried precipitate (g) 8. What mass of precipitate was collected? Show your work. (1) Calculate the percent yield for the reaction. Show your work. (2) 10. For your trial, which three ions were present in the filtered solution at the end of the reaction? In other words, which three ions are still dissolved at the end of the reaction? Defend/explain your 9. answer. (3) 11. Watch video C - watch both tests for your trial and record your observations. (1) a) Add lead (II) nitrate - b) Add potassium iodide - 12. These tests were conducted to prove the identity of the limiting reactant. Considering your answers to the previous two questions, describe how these tests support the prediction you made in question 5 about which compound is the limiting reactant. (2)

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英語 高校生

この問題を解いてください!!

77 読解時間2分52秒 回 Track 13 Can someone's birthday or *blood type influence their character? Some people believe so. Among young people, for instance, *horoscopes are very popular. There are twelve *astrological signs in a year, and your birthday tells you what sign you are. Horoscopes are based on these signs. They are often used to tell Someone's character. If you are born on April 1, for example, you belong to the sign, ** Aries.” People who believe in horoscopes say that anyone born under the sign of Aries is brave but a little careless. In addition to astrological signs, some people believe that your blood type has a lot to do with your character. For instance, a person with blood type A is said to be serious, a person with blood type B is said to be curious, a person with blood type AB is said to be artistic, and a person with blood type O is said to be very outgoing. In Japan, this blood type theory of character is very popular among people of all ages. Hundreds of books about blood types have been published, and some of them have become best sellers. Scientists say that there is no clear relation between astrological sign and character, or between blood type and character, yet many people are fond of asking others about their signs and blood types. It is true that not everyone believes in these theories, but for people who do, it can be a lot of fun to talk about and guess people's characters according to their blood type or sign. 258 words Jords & Phrases 1.1 blood type 血液型 1.6 Aries 名おひつじ座 1.2 horoscope 名星占い 1.3 astrological sign 星座

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