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人気のある三角関数 >

sin(2x)cos(x)-sin(x)=0

解

sin (2 x) cos (x) - sin (x) = 0

解

x = 2 πn, x = π + 2 πn, x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn, x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

+1

度

x = 0^{\circ} + 36 0^{\circ} n, x = 18 0^{\circ} + 36 0^{\circ} n, x = 13 5^{\circ} + 36 0^{\circ} n, x = 22 5^{\circ} + 36 0^{\circ} n, x = 4 5^{\circ} + 36 0^{\circ} n, x = 31 5^{\circ} + 36 0^{\circ} n

解答ステップ

sin (2 x) cos (x) - sin (x) = 0

三角関数の公式を使用して書き換える

- sin (x) + cos (x) sin (2 x)

2倍角の公式を使用:

sin (2 x) = 2 sin (x) cos (x)

= - sin (x) + cos (x) \cdot 2 sin (x) cos (x)

cos (x) \cdot 2 sin (x) cos (x) = 2 cos^{2} (x) sin (x)

cos (x) \cdot 2 sin (x) cos (x)

指数の規則を適用する:

a^{b} \cdot a^{c} = a^{b + c}

cos (x) cos (x) = cos^{1 + 1} (x)

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

数を足す:

1 + 1 = 2

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

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

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

因数

- sin (x) + 2 cos^{2} (x) sin (x) : sin (x) (2 cos (x) + 1) (2 cos (x) - 1)

- sin (x) + 2 cos^{2} (x) sin (x)

共通項をくくり出す

sin (x)

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

因数

2 cos^{2} (x) - 1 : (2 cos (x) + 1) (2 cos (x) - 1)

2 cos^{2} (x) - 1

2 cos^{2} (x) - 1

を書き換え

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

2 cos^{2} (x) - 1

累乗根の規則を適用する:

a = (a)^{2}

2 = (2)^{2}

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

1

を書き換え

1^{2}

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

指数の規則を適用する:

a^{m} b^{m} = (ab)^{m}

(2)^{2} cos^{2} (x) = (2 cos (x))^{2}

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

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

2乗の差の公式を適用する:

x^{2} - y^{2} = (x + y) (x - y)

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

= (2 cos (x) + 1) (2 cos (x) - 1)

= sin (x) (2 cos (x) + 1) (2 cos (x) - 1)

sin (x) (2 cos (x) + 1) (2 cos (x) - 1) = 0

各部分を別個に解く

sin (x) = 0 or 2 cos (x) + 1 = 0 or 2 cos (x) - 1 = 0

sin (x) = 0 : x = 2 πn, x = π + 2 πn

sin (x) = 0

以下の一般解

sin (x) = 0

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 = 0 + 2 πn, x = π + 2 πn

x = 0 + 2 πn, x = π + 2 πn

解く

x = 0 + 2 πn : x = 2 πn

x = 0 + 2 πn

0 + 2 πn = 2 πn

x = 2 πn

x = 2 πn, x = π + 2 πn

2 cos (x) + 1 = 0 : x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn

2 cos (x) + 1 = 0

1

を右側に移動します

2 cos (x) + 1 = 0

両辺から

1

を引く

2 cos (x) + 1 - 1 = 0 - 1

簡素化

2 cos (x) = - 1

2 cos (x) = - 1

以下で両辺を割る

2

2 cos (x) = - 1

以下で両辺を割る

2

\frac{2 cos ( x )}{2} = \frac{- 1}{2}

簡素化

\frac{2 cos ( x )}{2} = \frac{- 1}{2}

簡素化

\frac{2 cos ( x )}{2} : cos (x)

\frac{2 cos ( x )}{2}

共通因数を約分する:

2

= cos (x)

簡素化

\frac{- 1}{2} : - \frac{2}{2}

\frac{- 1}{2}

分数の規則を適用する:

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

= - \frac{1}{2}

有理化する

- \frac{1}{2} : - \frac{2}{2}

- \frac{1}{2}

共役で乗じる

\frac{2}{2}

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

1 \cdot 2 = 2

22 = 2

22

累乗根の規則を適用する:

a a = a

22 = 2

= 2

= - \frac{2}{2}

= - \frac{2}{2}

cos (x) = - \frac{2}{2}

cos (x) = - \frac{2}{2}

cos (x) = - \frac{2}{2}

以下の一般解

cos (x) = - \frac{2}{2}

cos (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} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{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} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn

x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn

2 cos (x) - 1 = 0 : x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

2 cos (x) - 1 = 0

1

を右側に移動します

2 cos (x) - 1 = 0

両辺に

1

を足す

2 cos (x) - 1 + 1 = 0 + 1

簡素化

2 cos (x) = 1

2 cos (x) = 1

以下で両辺を割る

2

2 cos (x) = 1

以下で両辺を割る

2

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

簡素化

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

簡素化

\frac{2 cos ( x )}{2} : cos (x)

\frac{2 cos ( x )}{2}

共通因数を約分する:

2

= cos (x)

簡素化

\frac{1}{2} : \frac{2}{2}

\frac{1}{2}

共役で乗じる

\frac{2}{2}

= \frac{1 \cdot 2}{2 2}

1 \cdot 2 = 2

22 = 2

22

累乗根の規則を適用する:

a a = a

22 = 2

= 2

= \frac{2}{2}

cos (x) = \frac{2}{2}

cos (x) = \frac{2}{2}

cos (x) = \frac{2}{2}

以下の一般解

cos (x) = \frac{2}{2}

cos (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} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{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} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

すべての解を組み合わせる

x = 2 πn, x = π + 2 πn, x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn, x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

グラフ

人気の例

9 sec^{2} (x) - 12 = 0

tan^2(x)-7tan(x)-8=0

tan^{2} (x) - 7 tan (x) - 8 = 0

5tan(x)sin(x)=-7sin(x)

5 tan (x) sin (x) = - 7 sin (x)

tan(x+pi)-cos(x+pi/2)=0

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2cos^2(θ)-9cos(θ)+4=0

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