ja

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

人気のある三角関数 >

3cos^2(x)-8cos(x)+4=sin^2(x)

解

3 cos^{2} (x) - 8 cos (x) + 4 = sin^{2} (x)

解

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

+1

度

x = 6 0^{\circ} + 36 0^{\circ} n, x = 30 0^{\circ} + 36 0^{\circ} n

解答ステップ

3 cos^{2} (x) - 8 cos (x) + 4 = sin^{2} (x)

両辺から

sin^{2} (x)

を引く

3 cos^{2} (x) - 8 cos (x) + 4 - sin^{2} (x) = 0

三角関数の公式を使用して書き換える

4 - sin^{2} (x) + 3 cos^{2} (x) - 8 cos (x)

ピタゴラスの公式を使用する:

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

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

= 4 - (1 - cos^{2} (x)) + 3 cos^{2} (x) - 8 cos (x)

簡素化

4 - (1 - cos^{2} (x)) + 3 cos^{2} (x) - 8 cos (x) : 4 cos^{2} (x) - 8 cos (x) + 3

4 - (1 - cos^{2} (x)) + 3 cos^{2} (x) - 8 cos (x)

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

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

括弧を分配する

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

マイナス・プラスの規則を適用する

- (- a) = a, - (a) = - a

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

= 4 - 1 + cos^{2} (x) + 3 cos^{2} (x) - 8 cos (x)

簡素化

4 - 1 + cos^{2} (x) + 3 cos^{2} (x) - 8 cos (x) : 4 cos^{2} (x) - 8 cos (x) + 3

4 - 1 + cos^{2} (x) + 3 cos^{2} (x) - 8 cos (x)

類似した元を足す:

cos^{2} (x) + 3 cos^{2} (x) = 4 cos^{2} (x)

= 4 - 1 + 4 cos^{2} (x) - 8 cos (x)

数を引く:

4 - 1 = 3

= 4 cos^{2} (x) - 8 cos (x) + 3

= 4 cos^{2} (x) - 8 cos (x) + 3

= 4 cos^{2} (x) - 8 cos (x) + 3

3 + 4 cos^{2} (x) - 8 cos (x) = 0

置換で解く

3 + 4 cos^{2} (x) - 8 cos (x) = 0

仮定:

cos (x) = u

3 + 4 u^{2} - 8 u = 0

3 + 4 u^{2} - 8 u = 0 : u = \frac{3}{2}, u = \frac{1}{2}

3 + 4 u^{2} - 8 u = 0

標準的な形式で書く

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

4 u^{2} - 8 u + 3 = 0

解くとthe二次式

4 u^{2} - 8 u + 3 = 0

二次Equationの公式:

次の場合:

a = 4, b = - 8, c = 3

u_{1, 2} = \frac{- ( - 8 ) \pm ( - 8 ) ^{2} - 4 \cdot 4 \cdot 3}{2 \cdot 4}

u_{1, 2} = \frac{- ( - 8 ) \pm ( - 8 ) ^{2} - 4 \cdot 4 \cdot 3}{2 \cdot 4}

(- 8)^{2} - 4 \cdot 4 \cdot 3 = 4

(- 8)^{2} - 4 \cdot 4 \cdot 3

指数の規則を適用する:

n

が偶数であれば

(- a)^{n} = a^{n}

(- 8)^{2} = 8^{2}

= 8^{2} - 4 \cdot 4 \cdot 3

数を乗じる:

4 \cdot 4 \cdot 3 = 48

= 8^{2} - 48

8^{2} = 64

= 64 - 48

数を引く:

64 - 48 = 16

= 16

数を因数に分解する:

16 = 4^{2}

= 4^{2}

累乗根の規則を適用する:

n a^{n} = a

4^{2} = 4

= 4

u_{1, 2} = \frac{- ( - 8 ) \pm 4}{2 \cdot 4}

解を分離する

u_{1} = \frac{- ( - 8 ) + 4}{2 \cdot 4}, u_{2} = \frac{- ( - 8 ) - 4}{2 \cdot 4}

u = \frac{- ( - 8 ) + 4}{2 \cdot 4} : \frac{3}{2}

\frac{- ( - 8 ) + 4}{2 \cdot 4}

規則を適用

- (- a) = a

= \frac{8 + 4}{2 \cdot 4}

数を足す:

8 + 4 = 12

= \frac{12}{2 \cdot 4}

数を乗じる:

2 \cdot 4 = 8

= \frac{12}{8}

共通因数を約分する:

4

= \frac{3}{2}

u = \frac{- ( - 8 ) - 4}{2 \cdot 4} : \frac{1}{2}

\frac{- ( - 8 ) - 4}{2 \cdot 4}

規則を適用

- (- a) = a

= \frac{8 - 4}{2 \cdot 4}

数を引く:

8 - 4 = 4

= \frac{4}{2 \cdot 4}

数を乗じる:

2 \cdot 4 = 8

= \frac{4}{8}

共通因数を約分する:

4

= \frac{1}{2}

二次equationの解:

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

代用を戻す

u = cos (x)

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

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

cos (x) = \frac{3}{2} :

解なし

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

- 1 \leq cos (x) \leq 1

解なし

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

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

以下の一般解

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

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

すべての解を組み合わせる

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

グラフ

人気の例

cos(x-45)=(-1)/2

cos (x - 4 5^{\circ}) = \frac{- 1}{2}

solvefor x,sin(x+r/4)+sin(x-r/3)=0

so l v e f or x, sin (x + \frac{r}{4}) + sin (x - \frac{r}{3}) = 0

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

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

solvefor x,sec(x)-sin(50o)=2

so l v e f or x, sec (x) - sin (50 o) = 2

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

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