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 >

cos(2x)=0.4

解答

cos (2 x) = 0.4

解答

x = \frac{1.15927 \dots}{2} + πn, x = π - \frac{1.15927 \dots}{2} + πn

+1

度数

x = 33.21091 \dots^{\circ} + 18 0^{\circ} n, x = 146.78908 \dots^{\circ} + 18 0^{\circ} n

求解步骤

cos (2 x) = 0.4

使用反三角函数性质

cos (2 x) = 0.4

cos (2 x) = 0.4

的通解

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

2 x = arccos (0.4) + 2 πn, 2 x = 2 π - arccos (0.4) + 2 πn

2 x = arccos (0.4) + 2 πn, 2 x = 2 π - arccos (0.4) + 2 πn

解

2 x = arccos (0.4) + 2 πn : x = \frac{arccos ( 0.4 )}{2} + πn

2 x = arccos (0.4) + 2 πn

两边除以

2

2 x = arccos (0.4) + 2 πn

两边除以

2

\frac{2 x}{2} = \frac{arccos ( 0.4 )}{2} + \frac{2 πn}{2}

化简

x = \frac{arccos ( 0.4 )}{2} + πn

x = \frac{arccos ( 0.4 )}{2} + πn

解

2 x = 2 π - arccos (0.4) + 2 πn : x = π - \frac{arccos ( 0.4 )}{2} + πn

2 x = 2 π - arccos (0.4) + 2 πn

两边除以

2

2 x = 2 π - arccos (0.4) + 2 πn

两边除以

2

\frac{2 x}{2} = \frac{2 π}{2} - \frac{arccos ( 0.4 )}{2} + \frac{2 πn}{2}

化简

x = π - \frac{arccos ( 0.4 )}{2} + πn

x = π - \frac{arccos ( 0.4 )}{2} + πn

x = \frac{arccos ( 0.4 )}{2} + πn, x = π - \frac{arccos ( 0.4 )}{2} + πn

以小数形式表示解

x = \frac{1.15927 \dots}{2} + πn, x = π - \frac{1.15927 \dots}{2} + πn

作图

流行的例子

arcsin(x)=(5pi)/6

arcsin (x) = \frac{5 π}{6}

2cos^2(t)-cos(t)=1

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

-2sin(t)+cos(2t)*2=0

- 2 sin (t) + cos (2 t) \cdot 2 = 0

tan (a) = \frac{4}{3}

5 sin (θ) - 1 = 0