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 >

3sin(x)cos(x)=sin(x)

解答

3 sin (x) cos (x) = sin (x)

解答

x = 2 πn, x = π + 2 πn, x = 1.23095 \dots + 2 πn, x = 2 π - 1.23095 \dots + 2 πn

+1

度数

x = 0^{\circ} + 36 0^{\circ} n, x = 18 0^{\circ} + 36 0^{\circ} n, x = 70.52877 \dots^{\circ} + 36 0^{\circ} n, x = 289.47122 \dots^{\circ} + 36 0^{\circ} n

求解步骤

3 sin (x) cos (x) = sin (x)

两边减去

sin (x)

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

分解

3 sin (x) cos (x) - sin (x) : sin (x) (3 cos (x) - 1)

3 sin (x) cos (x) - sin (x)

因式分解出通项

sin (x)

= sin (x) (3 cos (x) - 1)

sin (x) (3 cos (x) - 1) = 0

分别求解每个部分

sin (x) = 0 or 3 cos (x) - 1 = 0

sin (x) = 0 : x = 2 πn, x = π + 2 πn

sin (x) = 0

sin (x) = 0

的通解

sin (x)

周期表（周期为

2 πn

"）：

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

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

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

3 cos (x) - 1 = 0

将

1

到右边

3 cos (x) - 1 = 0

两边加上

1

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

化简

3 cos (x) = 1

3 cos (x) = 1

两边除以

3

3 cos (x) = 1

两边除以

3

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

化简

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

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

使用反三角函数性质

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

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

的通解

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

x = arccos (\frac{1}{3}) + 2 πn, x = 2 π - arccos (\frac{1}{3}) + 2 πn

x = arccos (\frac{1}{3}) + 2 πn, x = 2 π - arccos (\frac{1}{3}) + 2 πn

合并所有解

x = 2 πn, x = π + 2 πn, x = arccos (\frac{1}{3}) + 2 πn, x = 2 π - arccos (\frac{1}{3}) + 2 πn

以小数形式表示解

x = 2 πn, x = π + 2 πn, x = 1.23095 \dots + 2 πn, x = 2 π - 1.23095 \dots + 2 πn

作图

流行的例子

cos((5x}{10})=\frac{sqrt(2))/2

cos (\frac{5 x}{10}) = \frac{2}{2}

2cos(θ)tan(θ)-tan(θ)=0

2 cos (θ) tan (θ) - tan (θ) = 0

sqrt(2)=csc(θ)

2 = csc (θ)

cos^2(150)-sin^2(150)=tan(x)

cos^{2} (15 0^{\circ}) - sin^{2} (15 0^{\circ}) = tan (x)

3 - sin (x) = 0