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受欢迎的三角函数 >

cos(x+25)sec(65-x)=1

解答

cos (x + 2 5^{\circ}) sec (6 5^{\circ} - x) = 1

解答

x = 2 0^{\circ} - 18 0^{\circ} n

+1

弧度

x = \frac{π}{9} - πn

求解步骤

cos (x + 2 5^{\circ}) sec (6 5^{\circ} - x) = 1

两边减去

1

cos (x + 2 5^{\circ}) sec (6 5^{\circ} - x) - 1 = 0

化简

cos (x + 2 5^{\circ}) sec (6 5^{\circ} - x) - 1 : cos (\frac{36 x + 90 0 ^{\circ}}{36}) sec (\frac{234 0 ^{\circ} - 36 x}{36}) - 1

cos (x + 2 5^{\circ}) sec (6 5^{\circ} - x) - 1

cos (x + 2 5^{\circ}) sec (6 5^{\circ} - x) = cos (\frac{36 x + 90 0 ^{\circ}}{36}) sec (\frac{234 0 ^{\circ} - 36 x}{36})

cos (x + 2 5^{\circ}) sec (6 5^{\circ} - x)

化简

x + 2 5^{\circ} : \frac{36 x + 90 0 ^{\circ}}{36}

x + 2 5^{\circ}

将项转换为分式:

x = \frac{x 36}{36}

= \frac{x \cdot 36}{36} + 2 5^{\circ}

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{x \cdot 36 + 90 0 ^{\circ}}{36}

= cos (\frac{36 x + 90 0 ^{\circ}}{36}) sec (- x + 6 5^{\circ})

化简

6 5^{\circ} - x : \frac{234 0 ^{\circ} - 36 x}{36}

6 5^{\circ} - x

将项转换为分式:

x = \frac{x 36}{36}

= 6 5^{\circ} - \frac{x \cdot 36}{36}

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{234 0 ^{\circ} - x \cdot 36}{36}

= cos (\frac{36 x + 90 0 ^{\circ}}{36}) sec (\frac{- 36 x + 234 0 ^{\circ}}{36})

= cos (\frac{36 x + 90 0 ^{\circ}}{36}) sec (\frac{- 36 x + 234 0 ^{\circ}}{36}) - 1

cos (\frac{36 x + 90 0 ^{\circ}}{36}) sec (\frac{234 0 ^{\circ} - 36 x}{36}) - 1 = 0

使用三角恒等式改写

- 1 + cos (\frac{36 x + 90 0 ^{\circ}}{36}) sec (\frac{234 0 ^{\circ} - 36 x}{36})

利用以下特性:

cos (x) = sin (9 0^{\circ} - x)

= - 1 + sin (9 0^{\circ} - \frac{36 x + 90 0 ^{\circ}}{36}) sec (\frac{234 0 ^{\circ} - 36 x}{36})

化简

9 0^{\circ} - \frac{36 x + 90 0 ^{\circ}}{36} : \frac{- 36 x + 234 0 ^{\circ}}{36}

9 0^{\circ} - \frac{36 x + 90 0 ^{\circ}}{36}

2, 36

的最小公倍数:

36

2, 36

最小公倍数 (LCM)

2

质因数分解:

2

2

2

是质数，因此无法因数分解

= 2

36

质因数分解:

2 \cdot 2 \cdot 3 \cdot 3

36

36

除以

236 = 18 \cdot 2

= 2 \cdot 18

18

除以

218 = 9 \cdot 2

= 2 \cdot 2 \cdot 9

9

除以

39 = 3 \cdot 3

= 2 \cdot 2 \cdot 3 \cdot 3

2, 3

都是质数，因此无法进一步因数分解

= 2 \cdot 2 \cdot 3 \cdot 3

将每个因子乘以它在

2

或

36

中出现的最多次数

= 2 \cdot 2 \cdot 3 \cdot 3

数字相乘:

2 \cdot 2 \cdot 3 \cdot 3 = 36

= 36

根据最小公倍数调整分式

将每个分子乘以其分母转变为最小公倍数所要乘以的同一数值

36

对于

9 0^{\circ} :

将分母和分子乘以

18

9 0^{\circ} = \frac{18 0 ^{\circ} 18}{2 \cdot 18} = 9 0^{\circ}

= 9 0^{\circ} - \frac{36 x + 90 0 ^{\circ}}{36}

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{18 0 ^{\circ} 18 - ( 36 x + 90 0 ^{\circ} )}{36}

乘开

18 0^{\circ} 18 - (36 x + 90 0^{\circ}) : - 36 x + 234 0^{\circ}

18 0^{\circ} 18 - (36 x + 90 0^{\circ})

= 324 0^{\circ} - (36 x + 90 0^{\circ})

- (36 x + 90 0^{\circ}) : - 36 x - 90 0^{\circ}

- (36 x + 90 0^{\circ})

打开括号

= - (36 x) - (90 0^{\circ})

使用加减运算法则

+ (- a) = - a

= - 36 x - 90 0^{\circ}

= 18 0^{\circ} 18 - 36 x - 90 0^{\circ}

化简

18 0^{\circ} 18 - 36 x - 90 0^{\circ} : - 36 x + 234 0^{\circ}

18 0^{\circ} 18 - 36 x - 90 0^{\circ}

对同类项分组

= - 36 x + 324 0^{\circ} - 90 0^{\circ}

同类项相加:

324 0^{\circ} - 90 0^{\circ} = 234 0^{\circ}

= - 36 x + 234 0^{\circ}

= - 36 x + 234 0^{\circ}

= \frac{- 36 x + 234 0 ^{\circ}}{36}

= - 1 + sin (\frac{- 36 x + 234 0 ^{\circ}}{36}) sec (\frac{234 0 ^{\circ} - 36 x}{36})

sec (\frac{234 0 ^{\circ} - 36 x}{36}) sin (\frac{234 0 ^{\circ} - 36 x}{36}) = tan (\frac{234 0 ^{\circ} - 36 x}{36})

sec (\frac{234 0 ^{\circ} - 36 x}{36}) sin (\frac{234 0 ^{\circ} - 36 x}{36})

用 sin, cos 表示

sec (\frac{234 0 ^{\circ} - 36 x}{36}) sin (\frac{234 0 ^{\circ} - 36 x}{36})

使用基本三角恒等式:

sec (\frac{234 0 ^{\circ} - 36 x}{36}) = \frac{1}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )}

= \frac{1}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )} sin (\frac{234 0 ^{\circ} - 36 x}{36})

化简

\frac{1}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )} sin (\frac{234 0 ^{\circ} - 36 x}{36}) : \frac{sin ( \frac{234 0 ^{\circ} - 36 x}{36} )}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )}

\frac{1}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )} sin (\frac{234 0 ^{\circ} - 36 x}{36})

分式相乘:

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

= \frac{1 sin ( \frac{234 0 ^{\circ} - 36 x}{36} )}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )}

乘以:

1 \cdot sin (\frac{234 0 ^{\circ} - 36 x}{36}) = sin (\frac{234 0 ^{\circ} - 36 x}{36})

= \frac{sin ( \frac{234 0 ^{\circ} - 36 x}{36} )}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )}

= \frac{sin ( \frac{234 0 ^{\circ} - 36 x}{36} )}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )}

= \frac{sin ( \frac{234 0 ^{\circ} - 36 x}{36} )}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )}

使用基本三角恒等式:

\frac{sin ( \frac{234 0 ^{\circ} - 36 x}{36} )}{cos ( \frac{234 0 ^{\circ} - 36 x}{36} )} = tan (\frac{234 0 ^{\circ} - 36 x}{36})

= tan (\frac{234 0 ^{\circ} - 36 x}{36})

= - 1 + tan (\frac{234 0 ^{\circ} - 36 x}{36})

- 1 + tan (\frac{234 0 ^{\circ} - 36 x}{36}) = 0

将

1

到右边

- 1 + tan (\frac{234 0 ^{\circ} - 36 x}{36}) = 0

两边加上

1

- 1 + tan (\frac{234 0 ^{\circ} - 36 x}{36}) + 1 = 0 + 1

化简

tan (\frac{234 0 ^{\circ} - 36 x}{36}) = 1

tan (\frac{234 0 ^{\circ} - 36 x}{36}) = 1

tan (\frac{234 0 ^{\circ} - 36 x}{36}) = 1

的通解

tan (x)

周期表（周期为

18 0^{\circ} n

）：

x 0 3 0^{\circ} 4 5^{\circ} 6 0^{\circ} 9 0^{\circ} 12 0^{\circ} 13 5^{\circ} 15 0^{\circ} tan (x) 0 \frac{3}{3} 13 \pm \infty - 3 - 1 - \frac{3}{3}

\frac{234 0 ^{\circ} - 36 x}{36} = 4 5^{\circ} + 18 0^{\circ} n

\frac{234 0 ^{\circ} - 36 x}{36} = 4 5^{\circ} + 18 0^{\circ} n

解

\frac{234 0 ^{\circ} - 36 x}{36} = 4 5^{\circ} + 18 0^{\circ} n : x = 2 0^{\circ} - 18 0^{\circ} n

\frac{234 0 ^{\circ} - 36 x}{36} = 4 5^{\circ} + 18 0^{\circ} n

在两边乘以

36

\frac{234 0 ^{\circ} - 36 x}{36} = 4 5^{\circ} + 18 0^{\circ} n

在两边乘以

36

\frac{36 ( 234 0 ^{\circ} - 36 x )}{36} = 36 \cdot 4 5^{\circ} + 648 0^{\circ} n

化简

\frac{36 ( 234 0 ^{\circ} - 36 x )}{36} = 36 \cdot 4 5^{\circ} + 648 0^{\circ} n

化简

\frac{36 ( 234 0 ^{\circ} - 36 x )}{36} : 234 0^{\circ} - 36 x

\frac{36 ( 234 0 ^{\circ} - 36 x )}{36}

数字相除:

\frac{36}{36} = 1

= 234 0^{\circ} - 36 x

化简

36 \cdot 4 5^{\circ} + 648 0^{\circ} n : 162 0^{\circ} + 648 0^{\circ} n

36 \cdot 4 5^{\circ} + 648 0^{\circ} n

36 \cdot 4 5^{\circ} = 162 0^{\circ}

36 \cdot 4 5^{\circ}

分式相乘:

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

= 162 0^{\circ}

数字相除:

\frac{36}{4} = 9

= 162 0^{\circ}

= 162 0^{\circ} + 648 0^{\circ} n

234 0^{\circ} - 36 x = 162 0^{\circ} + 648 0^{\circ} n

234 0^{\circ} - 36 x = 162 0^{\circ} + 648 0^{\circ} n

234 0^{\circ} - 36 x = 162 0^{\circ} + 648 0^{\circ} n

将

234 0^{\circ}

到右边

234 0^{\circ} - 36 x = 162 0^{\circ} + 648 0^{\circ} n

两边减去

234 0^{\circ}

234 0^{\circ} - 36 x - 234 0^{\circ} = 162 0^{\circ} + 648 0^{\circ} n - 234 0^{\circ}

化简

- 36 x = - 72 0^{\circ} + 648 0^{\circ} n

- 36 x = - 72 0^{\circ} + 648 0^{\circ} n

两边除以

- 36

- 36 x = - 72 0^{\circ} + 648 0^{\circ} n

两边除以

- 36

\frac{- 36 x}{- 36} = - \frac{72 0 ^{\circ}}{- 36} + \frac{648 0 ^{\circ} n}{- 36}

化简

\frac{- 36 x}{- 36} = - \frac{72 0 ^{\circ}}{- 36} + \frac{648 0 ^{\circ} n}{- 36}

化简

\frac{- 36 x}{- 36} : x

\frac{- 36 x}{- 36}

使用分式法则:

\frac{- a}{- b} = \frac{a}{b}

= \frac{36 x}{36}

数字相除:

\frac{36}{36} = 1

= x

化简

- \frac{72 0 ^{\circ}}{- 36} + \frac{648 0 ^{\circ} n}{- 36} : 2 0^{\circ} - 18 0^{\circ} n

- \frac{72 0 ^{\circ}}{- 36} + \frac{648 0 ^{\circ} n}{- 36}

\frac{72 0 ^{\circ}}{- 36} = - 2 0^{\circ}

\frac{72 0 ^{\circ}}{- 36}

使用分式法则:

\frac{a}{- b} = - \frac{a}{b}

= - 2 0^{\circ}

约分:

4

= - 2 0^{\circ}

\frac{648 0 ^{\circ} n}{- 36} = - 18 0^{\circ} n

\frac{648 0 ^{\circ} n}{- 36}

使用分式法则:

\frac{a}{- b} = - \frac{a}{b}

= - \frac{648 0 ^{\circ} n}{36}

数字相除:

\frac{36}{36} = 1

= - 18 0^{\circ} n

= - (- 2 0^{\circ}) - 18 0^{\circ} n

使用法则

- (- a) = a

= 2 0^{\circ} - 18 0^{\circ} n

x = 2 0^{\circ} - 18 0^{\circ} n

x = 2 0^{\circ} - 18 0^{\circ} n

x = 2 0^{\circ} - 18 0^{\circ} n

x = 2 0^{\circ} - 18 0^{\circ} n

作图

流行的例子

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tan^{2} (x) - 5 tan (x) - 9 = 0

arctan(t)= pi/4

arctan (t) = \frac{π}{4}

tan (x) = - \frac{24}{7}

sec(θ)(sec(θ)-1)=2

sec (θ) (sec (θ) - 1) = 2

(sin(74))/8 =(sin(x))/4

\frac{sin ( 7 4 ^{\circ} )}{8} = \frac{sin ( x )}{4}