zs

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

受欢迎的三角函数 >

5cos^2(x)=4

解答

5 cos^{2} (x) = 4

解答

x = 0.46364 \dots + 2 πn, x = 2 π - 0.46364 \dots + 2 πn, x = 2.67794 \dots + 2 πn, x = - 2.67794 \dots + 2 πn

+1

度数

x = 26.56505 \dots^{\circ} + 36 0^{\circ} n, x = 333.43494 \dots^{\circ} + 36 0^{\circ} n, x = 153.43494 \dots^{\circ} + 36 0^{\circ} n, x = - 153.43494 \dots^{\circ} + 36 0^{\circ} n

求解步骤

5 cos^{2} (x) = 4

用替代法求解

5 cos^{2} (x) = 4

令

: cos (x) = u

5 u^{2} = 4

5 u^{2} = 4 : u = \frac{2 5}{5}, u = - \frac{2 5}{5}

5 u^{2} = 4

两边除以

5

5 u^{2} = 4

两边除以

5

\frac{5 u ^{2}}{5} = \frac{4}{5}

化简

u^{2} = \frac{4}{5}

u^{2} = \frac{4}{5}

对于

x^{2} = f (a)

解为

x = f (a), - f (a)

u = \frac{4}{5}, u = - \frac{4}{5}

\frac{4}{5} = \frac{2 5}{5}

\frac{4}{5}

使用根式运算法则:

n \frac{a}{b} = \frac{n a}{n b},

假定

a \geq 0, b \geq 0

= \frac{4}{5}

4 = 2

4

因式分解数字:

4 = 2^{2}

= 2^{2}

使用根式运算法则:

n a^{n} = a

2^{2} = 2

= 2

= \frac{2}{5}

\frac{2}{5}

有理化:

\frac{2 5}{5}

\frac{2}{5}

乘以共轭根式

\frac{5}{5}

= \frac{2 5}{5 5}

55 = 5

55

使用根式运算法则:

a a = a

55 = 5

= 5

= \frac{2 5}{5}

= \frac{2 5}{5}

- \frac{4}{5} = - \frac{2 5}{5}

- \frac{4}{5}

化简

\frac{4}{5} : \frac{2}{5}

\frac{4}{5}

使用根式运算法则:

n \frac{a}{b} = \frac{n a}{n b},

假定

a \geq 0, b \geq 0

= \frac{4}{5}

4 = 2

4

因式分解数字:

4 = 2^{2}

= 2^{2}

使用根式运算法则:

n a^{n} = a

2^{2} = 2

= 2

= \frac{2}{5}

= - \frac{2}{5}

- \frac{2}{5}

有理化:

- \frac{2 5}{5}

- \frac{2}{5}

乘以共轭根式

\frac{5}{5}

= - \frac{2 5}{5 5}

55 = 5

55

使用根式运算法则:

a a = a

55 = 5

= 5

= - \frac{2 5}{5}

= - \frac{2 5}{5}

u = \frac{2 5}{5}, u = - \frac{2 5}{5}

u = cos (x)

代回

cos (x) = \frac{2 5}{5}, cos (x) = - \frac{2 5}{5}

cos (x) = \frac{2 5}{5}, cos (x) = - \frac{2 5}{5}

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

cos (x) = \frac{2 5}{5}

使用反三角函数性质

cos (x) = \frac{2 5}{5}

cos (x) = \frac{2 5}{5}

的通解

cos (x) = a \Rightarrow x = arccos (a) + 2 πn, x = 2 π - arccos (a) + 2 πn

x = arccos (\frac{2 5}{5}) + 2 πn, x = 2 π - arccos (\frac{2 5}{5}) + 2 πn

x = arccos (\frac{2 5}{5}) + 2 πn, x = 2 π - arccos (\frac{2 5}{5}) + 2 πn

cos (x) = - \frac{2 5}{5} : x = arccos (- \frac{2 5}{5}) + 2 πn, x = - arccos (- \frac{2 5}{5}) + 2 πn

cos (x) = - \frac{2 5}{5}

使用反三角函数性质

cos (x) = - \frac{2 5}{5}

cos (x) = - \frac{2 5}{5}

的通解

cos (x) = - a \Rightarrow x = arccos (- a) + 2 πn, x = - arccos (- a) + 2 πn

x = arccos (- \frac{2 5}{5}) + 2 πn, x = - arccos (- \frac{2 5}{5}) + 2 πn

x = arccos (- \frac{2 5}{5}) + 2 πn, x = - arccos (- \frac{2 5}{5}) + 2 πn

合并所有解

x = arccos (\frac{2 5}{5}) + 2 πn, x = 2 π - arccos (\frac{2 5}{5}) + 2 πn, x = arccos (- \frac{2 5}{5}) + 2 πn, x = - arccos (- \frac{2 5}{5}) + 2 πn

以小数形式表示解

x = 0.46364 \dots + 2 πn, x = 2 π - 0.46364 \dots + 2 πn, x = 2.67794 \dots + 2 πn, x = - 2.67794 \dots + 2 πn

作图

流行的例子

cos(x-15^0)=((sqrt(2)))/2

cos (x - 1 5^{0}) = \frac{( 2 )}{2}

sin(x)=1-cos^x(x)

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

4-7sin(x)=cos^2(x)

4 - 7 sin (x) = cos^{2} (x)

(d^2-2d+3)=sin(x)

(d^{2} - 2 d + 3) = sin (x)

\frac{5}{tan ( x )} = - 2