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人気のある三角関数 >

3cos(2x)+7sin(x)-5=0

解

3 cos (2 x) + 7 sin (x) - 5 = 0

解

x = \frac{π}{6} + 2 πn, x = \frac{5 π}{6} + 2 πn, x = 0.72972 \dots + 2 πn, x = π - 0.72972 \dots + 2 πn

+1

度

x = 3 0^{\circ} + 36 0^{\circ} n, x = 15 0^{\circ} + 36 0^{\circ} n, x = 41.81031 \dots^{\circ} + 36 0^{\circ} n, x = 138.18968 \dots^{\circ} + 36 0^{\circ} n

解答ステップ

3 cos (2 x) + 7 sin (x) - 5 = 0

三角関数の公式を使用して書き換える

- 5 + 3 cos (2 x) + 7 sin (x)

2倍角の公式を使用:

cos (2 x) = 1 - 2 sin^{2} (x)

= - 5 + 3 (1 - 2 sin^{2} (x)) + 7 sin (x)

簡素化

- 5 + 3 (1 - 2 sin^{2} (x)) + 7 sin (x) : 7 sin (x) - 6 sin^{2} (x) - 2

- 5 + 3 (1 - 2 sin^{2} (x)) + 7 sin (x)

拡張

3 (1 - 2 sin^{2} (x)) : 3 - 6 sin^{2} (x)

3 (1 - 2 sin^{2} (x))

分配法則を適用する:

a (b - c) = ab - a c

a = 3, b = 1, c = 2 sin^{2} (x)

= 3 \cdot 1 - 3 \cdot 2 sin^{2} (x)

簡素化

3 \cdot 1 - 3 \cdot 2 sin^{2} (x) : 3 - 6 sin^{2} (x)

3 \cdot 1 - 3 \cdot 2 sin^{2} (x)

数を乗じる:

3 \cdot 1 = 3

= 3 - 3 \cdot 2 sin^{2} (x)

数を乗じる:

3 \cdot 2 = 6

= 3 - 6 sin^{2} (x)

= 3 - 6 sin^{2} (x)

= - 5 + 3 - 6 sin^{2} (x) + 7 sin (x)

数を足す/引く:

- 5 + 3 = - 2

= 7 sin (x) - 6 sin^{2} (x) - 2

= 7 sin (x) - 6 sin^{2} (x) - 2

- 2 - 6 sin^{2} (x) + 7 sin (x) = 0

置換で解く

- 2 - 6 sin^{2} (x) + 7 sin (x) = 0

仮定:

sin (x) = u

- 2 - 6 u^{2} + 7 u = 0

- 2 - 6 u^{2} + 7 u = 0 : u = \frac{1}{2}, u = \frac{2}{3}

- 2 - 6 u^{2} + 7 u = 0

標準的な形式で書く

a x^{2} + b x + c = 0

- 6 u^{2} + 7 u - 2 = 0

解くとthe二次式

- 6 u^{2} + 7 u - 2 = 0

二次Equationの公式:

次の場合:

a = - 6, b = 7, c = - 2

u_{1, 2} = \frac{- 7 \pm 7 ^{2} - 4 ( - 6 ) ( - 2 )}{2 ( - 6 )}

u_{1, 2} = \frac{- 7 \pm 7 ^{2} - 4 ( - 6 ) ( - 2 )}{2 ( - 6 )}

7^{2} - 4 (- 6) (- 2) = 1

7^{2} - 4 (- 6) (- 2)

規則を適用

- (- a) = a

= 7^{2} - 4 \cdot 6 \cdot 2

数を乗じる:

4 \cdot 6 \cdot 2 = 48

= 7^{2} - 48

7^{2} = 49

= 49 - 48

数を引く:

49 - 48 = 1

= 1

規則を適用

1 = 1

= 1

u_{1, 2} = \frac{- 7 \pm 1}{2 ( - 6 )}

解を分離する

u_{1} = \frac{- 7 + 1}{2 ( - 6 )}, u_{2} = \frac{- 7 - 1}{2 ( - 6 )}

u = \frac{- 7 + 1}{2 ( - 6 )} : \frac{1}{2}

\frac{- 7 + 1}{2 ( - 6 )}

括弧を削除する:

(- a) = - a

= \frac{- 7 + 1}{- 2 \cdot 6}

数を足す/引く:

- 7 + 1 = - 6

= \frac{- 6}{- 2 \cdot 6}

数を乗じる:

2 \cdot 6 = 12

= \frac{- 6}{- 12}

分数の規則を適用する:

\frac{- a}{- b} = \frac{a}{b}

= \frac{6}{12}

共通因数を約分する:

6

= \frac{1}{2}

u = \frac{- 7 - 1}{2 ( - 6 )} : \frac{2}{3}

\frac{- 7 - 1}{2 ( - 6 )}

括弧を削除する:

(- a) = - a

= \frac{- 7 - 1}{- 2 \cdot 6}

数を引く:

- 7 - 1 = - 8

= \frac{- 8}{- 2 \cdot 6}

数を乗じる:

2 \cdot 6 = 12

= \frac{- 8}{- 12}

分数の規則を適用する:

\frac{- a}{- b} = \frac{a}{b}

= \frac{8}{12}

共通因数を約分する:

4

= \frac{2}{3}

二次equationの解:

u = \frac{1}{2}, u = \frac{2}{3}

代用を戻す

u = sin (x)

sin (x) = \frac{1}{2}, sin (x) = \frac{2}{3}

sin (x) = \frac{1}{2}, sin (x) = \frac{2}{3}

sin (x) = \frac{1}{2} : x = \frac{π}{6} + 2 πn, x = \frac{5 π}{6} + 2 πn

sin (x) = \frac{1}{2}

以下の一般解

sin (x) = \frac{1}{2}

sin (x)

2 πn

循環を含む周期性テーブル:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

x = \frac{π}{6} + 2 πn, x = \frac{5 π}{6} + 2 πn

x = \frac{π}{6} + 2 πn, x = \frac{5 π}{6} + 2 πn

sin (x) = \frac{2}{3} : x = arcsin (\frac{2}{3}) + 2 πn, x = π - arcsin (\frac{2}{3}) + 2 πn

sin (x) = \frac{2}{3}

三角関数の逆数プロパティを適用する

sin (x) = \frac{2}{3}

以下の一般解

sin (x) = \frac{2}{3}

sin (x) = a \Rightarrow x = arcsin (a) + 2 πn, x = π - arcsin (a) + 2 πn

x = arcsin (\frac{2}{3}) + 2 πn, x = π - arcsin (\frac{2}{3}) + 2 πn

x = arcsin (\frac{2}{3}) + 2 πn, x = π - arcsin (\frac{2}{3}) + 2 πn

すべての解を組み合わせる

x = \frac{π}{6} + 2 πn, x = \frac{5 π}{6} + 2 πn, x = arcsin (\frac{2}{3}) + 2 πn, x = π - arcsin (\frac{2}{3}) + 2 πn

10進法形式で解を証明する

x = \frac{π}{6} + 2 πn, x = \frac{5 π}{6} + 2 πn, x = 0.72972 \dots + 2 πn, x = π - 0.72972 \dots + 2 πn

グラフ

人気の例

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