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人気のある三角関数 >

8sin(2x)sin(x)=8cos(x)

解

8 sin (2 x) sin (x) = 8 cos (x)

解

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

+1

度

x = 9 0^{\circ} + 36 0^{\circ} n, x = 27 0^{\circ} + 36 0^{\circ} n, x = 22 5^{\circ} + 36 0^{\circ} n, x = 31 5^{\circ} + 36 0^{\circ} n, x = 4 5^{\circ} + 36 0^{\circ} n, x = 13 5^{\circ} + 36 0^{\circ} n

解答ステップ

8 sin (2 x) sin (x) = 8 cos (x)

両辺から

8 cos (x)

を引く

8 sin (2 x) sin (x) - 8 cos (x) = 0

三角関数の公式を使用して書き換える

- 8 cos (x) + 8 sin (2 x) sin (x)

2倍角の公式を使用:

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

= - 8 cos (x) + 8 \cdot 2 sin (x) cos (x) sin (x)

8 \cdot 2 sin (x) cos (x) sin (x) = 16 sin^{2} (x) cos (x)

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

数を乗じる:

8 \cdot 2 = 16

= 16 sin (x) cos (x) sin (x)

指数の規則を適用する:

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

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

= 16 cos (x) sin^{1 + 1} (x)

数を足す:

1 + 1 = 2

= 16 cos (x) sin^{2} (x)

= - 8 cos (x) + 16 sin^{2} (x) cos (x)

- 8 cos (x) + 16 cos (x) sin^{2} (x) = 0

因数

- 8 cos (x) + 16 cos (x) sin^{2} (x) : 8 cos (x) (2 sin (x) + 1) (2 sin (x) - 1)

- 8 cos (x) + 16 cos (x) sin^{2} (x)

16

を書き換え

2 \cdot 8

= - 8 cos (x) + 2 \cdot 8 sin^{2} (x) cos (x)

共通項をくくり出す

8 cos (x)

= 8 cos (x) (- 1 + 2 sin^{2} (x))

因数

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

2 sin^{2} (x) - 1

2 sin^{2} (x) - 1

を書き換え

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

2 sin^{2} (x) - 1

累乗根の規則を適用する:

a = (a)^{2}

2 = (2)^{2}

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

1

を書き換え

1^{2}

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

指数の規則を適用する:

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

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

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

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

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

= 8 cos (x) (2 sin (x) + 1) (2 sin (x) - 1)

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

各部分を別個に解く

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

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

cos (x) = 0

以下の一般解

cos (x) = 0

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}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn

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

2 sin (x) + 1 = 0 : x = \frac{5 π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

2 sin (x) + 1 = 0

1

を右側に移動します

2 sin (x) + 1 = 0

両辺から

1

を引く

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

簡素化

2 sin (x) = - 1

2 sin (x) = - 1

以下で両辺を割る

2

2 sin (x) = - 1

以下で両辺を割る

2

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

簡素化

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

簡素化

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

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

共通因数を約分する:

2

= sin (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}

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

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

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

以下の一般解

sin (x) = - \frac{2}{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{5 π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

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

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

2 sin (x) - 1 = 0

1

を右側に移動します

2 sin (x) - 1 = 0

両辺に

1

を足す

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

簡素化

2 sin (x) = 1

2 sin (x) = 1

以下で両辺を割る

2

2 sin (x) = 1

以下で両辺を割る

2

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

簡素化

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

簡素化

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

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

共通因数を約分する:

2

= sin (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}

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

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

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

以下の一般解

sin (x) = \frac{2}{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}{4} + 2 πn, x = \frac{3 π}{4} + 2 πn

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

すべての解を組み合わせる

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

グラフ

人気の例

cos (x) = - \frac{3}{4}

2cos^2(x)+cos(x)-1=0,0<= x<= 2pi

2 cos^{2} (x) + cos (x) - 1 = 0, 0 \leq x \leq 2 π

arcsin(x)-arccos(-1/2)= pi/6

arcsin (x) - arccos (- \frac{1}{2}) = \frac{π}{6}

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

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

tan^3(x)=3tan(x)

tan^{3} (x) = 3 tan (x)