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 >

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

解答

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

解答

x = 2 πn, x = \frac{π}{4} + πn

+1

度数

x = 0^{\circ} + 36 0^{\circ} n, x = 4 5^{\circ} + 18 0^{\circ} n

求解步骤

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

两边减去

cos (x) - 1

sin (x) - tan (x) - cos (x) + 1 = 0

用 sin, cos 表示

1 - cos (x) + sin (x) - tan (x)

使用基本三角恒等式:

tan (x) = \frac{sin ( x )}{cos ( x )}

= 1 - cos (x) + sin (x) - \frac{sin ( x )}{cos ( x )}

化简

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

1 - cos (x) + sin (x) - \frac{sin ( x )}{cos ( x )}

将项转换为分式:

1 = \frac{1 cos ( x )}{cos ( x )}, cos (x) = \frac{cos ( x ) cos ( x )}{cos ( x )}, sin (x) = \frac{sin ( x ) cos ( x )}{cos ( x )}

= \frac{1 \cdot cos ( x )}{cos ( x )} - \frac{cos ( x ) cos ( x )}{cos ( x )} + \frac{sin ( x ) cos ( x )}{cos ( x )} - \frac{sin ( x )}{cos ( x )}

因为分母相等，所以合并分式:

\frac{a}{c} \pm \frac{b}{c} = \frac{a \pm b}{c}

= \frac{1 \cdot cos ( x ) - cos ( x ) cos ( x ) + sin ( x ) cos ( x ) - sin ( x )}{cos ( x )}

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

1 \cdot cos (x) - cos (x) cos (x) + sin (x) cos (x) - sin (x)

1 \cdot cos (x) = cos (x)

1 \cdot cos (x)

乘以:

1 \cdot cos (x) = cos (x)

= cos (x)

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

cos (x) cos (x)

使用指数法则:

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

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

= cos^{1 + 1} (x)

数字相加:

1 + 1 = 2

= cos^{2} (x)

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

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

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

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

\frac{f ( x )}{g ( x )} = 0 \Rightarrow f (x) = 0

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

分解

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

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

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

从

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

分解出因式

sin (x)

:

sin (x) (cos (x) - 1)

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

因式分解出通项

sin (x)

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

从

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

分解出因式

- cos (x)

:

- cos (x) (cos (x) - 1)

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

使用指数法则:

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

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

= - cos (x) cos (x) + cos (x)

因式分解出通项

- cos (x)

= - cos (x) (cos (x) - 1)

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

因式分解出通项

cos (x) - 1

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

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

分别求解每个部分

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

cos (x) - 1 = 0 : x = 2 πn

cos (x) - 1 = 0

将

1

到右边

cos (x) - 1 = 0

两边加上

1

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

化简

cos (x) = 1

cos (x) = 1

cos (x) = 1

的通解

cos (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} 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 = 0 + 2 πn

x = 0 + 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

sin (x) - cos (x) = 0 : x = \frac{π}{4} + πn

sin (x) - cos (x) = 0

使用三角恒等式改写

sin (x) - cos (x) = 0

在两边除以

cos (x), cos (x) \neq = 0

\frac{sin ( x ) - cos ( x )}{cos ( x )} = \frac{0}{cos ( x )}

化简

\frac{sin ( x )}{cos ( x )} - 1 = 0

使用基本三角恒等式:

\frac{sin ( x )}{cos ( x )} = tan (x)

tan (x) - 1 = 0

tan (x) - 1 = 0

将

1

到右边

tan (x) - 1 = 0

两边加上

1

tan (x) - 1 + 1 = 0 + 1

化简

tan (x) = 1

tan (x) = 1

tan (x) = 1

的通解

tan (x)

周期表（周期为

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} tan (x) 0 \frac{3}{3} 13 \pm \infty - 3 - 1 - \frac{3}{3}

x = \frac{π}{4} + πn

x = \frac{π}{4} + πn

合并所有解

x = 2 πn, x = \frac{π}{4} + πn

作图

流行的例子

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

sin(2θ-pi/2)=1

sin (2 θ - \frac{π}{2}) = 1

2sin^2(2θ)=1-sin(2θ)

2 sin^{2} (2 θ) = 1 - sin (2 θ)

cos (θ) = \frac{24}{25}

sec^2(x)=1-tan^2(x)

sec^{2} (x) = 1 - tan^{2} (x)