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受欢迎的三角函数 >

tan(54)

解答

tan (5 4^{\circ})

解答

\frac{( 3 10 + 5 2 ) 5 - 5}{20}

+1

十进制

1.37638 \dots

求解步骤

tan (5 4^{\circ})

使用三角恒等式改写:

\frac{sin ( 5 4 ^{\circ} )}{cos ( 5 4 ^{\circ} )}

tan (5 4^{\circ})

使用基本三角恒等式:

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

= \frac{sin ( 5 4 ^{\circ} )}{cos ( 5 4 ^{\circ} )}

= \frac{sin ( 5 4 ^{\circ} )}{cos ( 5 4 ^{\circ} )}

使用三角恒等式改写:

sin (5 4^{\circ}) = \frac{5 + 1}{4}

sin (5 4^{\circ})

使用三角恒等式改写:

cos (3 6^{\circ})

sin (5 4^{\circ})

利用以下特性:

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

= cos (9 0^{\circ} - 5 4^{\circ})

化简

= cos (3 6^{\circ})

= cos (3 6^{\circ})

使用三角恒等式改写:

\frac{5 + 1}{4}

cos (3 6^{\circ})

显示:

cos (3 6^{\circ}) - sin (1 8^{\circ}) = \frac{1}{2}

使用以下积化和差公式:

2 sin (x) cos (y) = sin (x + y) - sin (x - y)

2 cos (3 6^{\circ}) sin (1 8^{\circ}) = sin (5 4^{\circ}) - sin (1 8^{\circ})

显示:

2 cos (3 6^{\circ}) sin (1 8^{\circ}) = \frac{1}{2}

使用倍角公式:

sin (2 x) = 2 sin (x) cos (x)

sin (7 2^{\circ}) = 2 sin (3 6^{\circ}) cos (3 6^{\circ})

sin (7 2^{\circ}) sin (3 6^{\circ}) = 4 sin (3 6^{\circ}) sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

两边除以

sin (3 6^{\circ})

sin (7 2^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

利用以下特性:

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

sin (7 2^{\circ}) = cos (9 0^{\circ} - 7 2^{\circ})

cos (9 0^{\circ} - 7 2^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

cos (1 8^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

两边除以

cos (1 8^{\circ})

1 = 4 sin (1 8^{\circ}) cos (3 6^{\circ})

两边除以

2

\frac{1}{2} = 2 sin (1 8^{\circ}) cos (3 6^{\circ})

代入

\frac{1}{2} = 2 sin (1 8^{\circ}) cos (3 6^{\circ})

\frac{1}{2} = sin (5 4^{\circ}) - sin (1 8^{\circ})

sin (5 4^{\circ}) = cos (9 0^{\circ} - 5 4^{\circ})

\frac{1}{2} = cos (9 0^{\circ} - 5 4^{\circ}) - sin (1 8^{\circ})

\frac{1}{2} = cos (3 6^{\circ}) - sin (1 8^{\circ})

显示:

cos (3 6^{\circ}) + sin (1 8^{\circ}) = \frac{5}{4}

使用因式分解法则:

a^{2} - b^{2} = (a + b) (a - b)

a = cos (3 6^{\circ}) + sin (1 8^{\circ})

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - (cos (3 6^{\circ}) - sin (1 8^{\circ}))^{2} = ((cos (3 6^{\circ}) + sin (1 8^{\circ})) + (cos (3 6^{\circ}) - sin (1 8^{\circ}))) ((cos (3 6^{\circ}) + sin (1 8^{\circ})) - (cos (3 6^{\circ}) - sin (1 8^{\circ})))

整理后得

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - (cos (3 6^{\circ}) - sin (1 8^{\circ}))^{2} = 2 (2 cos (3 6^{\circ}) sin (1 8^{\circ}))

显示:

2 cos (3 6^{\circ}) sin (1 8^{\circ}) = \frac{1}{2}

使用倍角公式:

sin (2 x) = 2 sin (x) cos (x)

sin (7 2^{\circ}) = 2 sin (3 6^{\circ}) cos (3 6^{\circ})

sin (7 2^{\circ}) sin (3 6^{\circ}) = 4 sin (3 6^{\circ}) sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

两边除以

sin (3 6^{\circ})

sin (7 2^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

利用以下特性:

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

sin (7 2^{\circ}) = cos (9 0^{\circ} - 7 2^{\circ})

cos (9 0^{\circ} - 7 2^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

cos (1 8^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

两边除以

cos (1 8^{\circ})

1 = 4 sin (1 8^{\circ}) cos (3 6^{\circ})

两边除以

2

\frac{1}{2} = 2 sin (1 8^{\circ}) cos (3 6^{\circ})

代入

2 cos (3 6^{\circ}) sin (1 8^{\circ}) = \frac{1}{2}

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - (cos (3 6^{\circ}) - sin (1 8^{\circ}))^{2} = 1

代入

cos (3 6^{\circ}) - sin (1 8^{\circ}) = \frac{1}{2}

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - (\frac{1}{2})^{2} = 1

整理后得

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - \frac{1}{4} = 1

两边加上

\frac{1}{4}

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - \frac{1}{4} + \frac{1}{4} = 1 + \frac{1}{4}

整理后得

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} = \frac{5}{4}

在两侧开平方

cos (3 6^{\circ}) + sin (1 8^{\circ}) = \pm \frac{5}{4}

cos (3 6^{\circ})

不能为负

sin (1 8^{\circ})

不能为负

cos (3 6^{\circ}) + sin (1 8^{\circ}) = \frac{5}{4}

以下方程式相加

cos (3 6^{\circ}) + sin (1 8^{\circ}) = \frac{5}{2}

((cos (3 6^{\circ}) + sin (1 8^{\circ})) + (cos (3 6^{\circ}) - sin (1 8^{\circ}))) = (\frac{5}{2} + \frac{1}{2})

整理后得

cos (3 6^{\circ}) = \frac{5 + 1}{4}

= \frac{5 + 1}{4}

= \frac{5 + 1}{4}

使用三角恒等式改写:

cos (5 4^{\circ}) = \frac{2 5 - 5}{4}

cos (5 4^{\circ})

使用三角恒等式改写:

sin (3 6^{\circ})

cos (5 4^{\circ})

利用以下特性:

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

= sin (9 0^{\circ} - 5 4^{\circ})

化简

= sin (3 6^{\circ})

= sin (3 6^{\circ})

使用三角恒等式改写:

\frac{2 5 - 5}{4}

sin (3 6^{\circ})

显示:

cos (3 6^{\circ}) - sin (1 8^{\circ}) = \frac{1}{2}

使用以下积化和差公式:

2 sin (x) cos (y) = sin (x + y) - sin (x - y)

2 cos (3 6^{\circ}) sin (1 8^{\circ}) = sin (5 4^{\circ}) - sin (1 8^{\circ})

显示:

2 cos (3 6^{\circ}) sin (1 8^{\circ}) = \frac{1}{2}

使用倍角公式:

sin (2 x) = 2 sin (x) cos (x)

sin (7 2^{\circ}) = 2 sin (3 6^{\circ}) cos (3 6^{\circ})

sin (7 2^{\circ}) sin (3 6^{\circ}) = 4 sin (3 6^{\circ}) sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

两边除以

sin (3 6^{\circ})

sin (7 2^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

利用以下特性:

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

sin (7 2^{\circ}) = cos (9 0^{\circ} - 7 2^{\circ})

cos (9 0^{\circ} - 7 2^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

cos (1 8^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

两边除以

cos (1 8^{\circ})

1 = 4 sin (1 8^{\circ}) cos (3 6^{\circ})

两边除以

2

\frac{1}{2} = 2 sin (1 8^{\circ}) cos (3 6^{\circ})

代入

\frac{1}{2} = 2 sin (1 8^{\circ}) cos (3 6^{\circ})

\frac{1}{2} = sin (5 4^{\circ}) - sin (1 8^{\circ})

sin (5 4^{\circ}) = cos (9 0^{\circ} - 5 4^{\circ})

\frac{1}{2} = cos (9 0^{\circ} - 5 4^{\circ}) - sin (1 8^{\circ})

\frac{1}{2} = cos (3 6^{\circ}) - sin (1 8^{\circ})

显示:

cos (3 6^{\circ}) + sin (1 8^{\circ}) = \frac{5}{4}

使用因式分解法则:

a^{2} - b^{2} = (a + b) (a - b)

a = cos (3 6^{\circ}) + sin (1 8^{\circ})

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - (cos (3 6^{\circ}) - sin (1 8^{\circ}))^{2} = ((cos (3 6^{\circ}) + sin (1 8^{\circ})) + (cos (3 6^{\circ}) - sin (1 8^{\circ}))) ((cos (3 6^{\circ}) + sin (1 8^{\circ})) - (cos (3 6^{\circ}) - sin (1 8^{\circ})))

整理后得

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - (cos (3 6^{\circ}) - sin (1 8^{\circ}))^{2} = 2 (2 cos (3 6^{\circ}) sin (1 8^{\circ}))

显示:

2 cos (3 6^{\circ}) sin (1 8^{\circ}) = \frac{1}{2}

使用倍角公式:

sin (2 x) = 2 sin (x) cos (x)

sin (7 2^{\circ}) = 2 sin (3 6^{\circ}) cos (3 6^{\circ})

sin (7 2^{\circ}) sin (3 6^{\circ}) = 4 sin (3 6^{\circ}) sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

两边除以

sin (3 6^{\circ})

sin (7 2^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

利用以下特性:

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

sin (7 2^{\circ}) = cos (9 0^{\circ} - 7 2^{\circ})

cos (9 0^{\circ} - 7 2^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

cos (1 8^{\circ}) = 4 sin (1 8^{\circ}) cos (3 6^{\circ}) cos (1 8^{\circ})

两边除以

cos (1 8^{\circ})

1 = 4 sin (1 8^{\circ}) cos (3 6^{\circ})

两边除以

2

\frac{1}{2} = 2 sin (1 8^{\circ}) cos (3 6^{\circ})

代入

2 cos (3 6^{\circ}) sin (1 8^{\circ}) = \frac{1}{2}

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - (cos (3 6^{\circ}) - sin (1 8^{\circ}))^{2} = 1

代入

cos (3 6^{\circ}) - sin (1 8^{\circ}) = \frac{1}{2}

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - (\frac{1}{2})^{2} = 1

整理后得

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - \frac{1}{4} = 1

两边加上

\frac{1}{4}

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} - \frac{1}{4} + \frac{1}{4} = 1 + \frac{1}{4}

整理后得

(cos (3 6^{\circ}) + sin (1 8^{\circ}))^{2} = \frac{5}{4}

在两侧开平方

cos (3 6^{\circ}) + sin (1 8^{\circ}) = \pm \frac{5}{4}

cos (3 6^{\circ})

不能为负

sin (1 8^{\circ})

不能为负

cos (3 6^{\circ}) + sin (1 8^{\circ}) = \frac{5}{4}

以下方程式相加

cos (3 6^{\circ}) + sin (1 8^{\circ}) = \frac{5}{2}

((cos (3 6^{\circ}) + sin (1 8^{\circ})) + (cos (3 6^{\circ}) - sin (1 8^{\circ}))) = (\frac{5}{2} + \frac{1}{2})

整理后得

cos (3 6^{\circ}) = \frac{5 + 1}{4}

两边进行平方

(cos (3 6^{\circ}))^{2} = (\frac{5 + 1}{4})^{2}

利用以下特性:

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

sin^{2} (3 6^{\circ}) = 1 - cos^{2} (3 6^{\circ})

代入

cos (3 6^{\circ}) = \frac{5 + 1}{4}

sin^{2} (3 6^{\circ}) = 1 - (\frac{5 + 1}{4})^{2}

整理后得

sin^{2} (3 6^{\circ}) = \frac{5 - 5}{8}

在两侧开平方

sin (3 6^{\circ}) = \pm \frac{5 - 5}{8}

sin (3 6^{\circ})

不能为负

sin (3 6^{\circ}) = \frac{5 - 5}{8}

整理后得

sin (3 6^{\circ}) = \frac{\frac{5 - 5}{2}}{2}

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

化简

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

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

= \frac{\frac{5 + 1}{4}}{\frac{2 5 - 5}{4}}

化简

\frac{\frac{5 + 1}{4}}{\frac{2 5 - 5}{4}} : \frac{( 3 10 + 5 2 ) 5 - 5}{20}

\frac{\frac{5 + 1}{4}}{\frac{2 5 - 5}{4}}

分式相除:

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

= \frac{( 5 + 1 ) \cdot 4}{4 2 5 - 5}

约分:

4

= \frac{5 + 1}{2 5 - 5}

\frac{5 + 1}{2 5 - 5}

有理化:

\frac{( 3 10 + 5 2 ) 5 - 5}{20}

\frac{5 + 1}{2 5 - 5}

乘以共轭根式

\frac{2}{2}

= \frac{( 5 + 1 ) 2}{2 5 - 5 2}

2 5 - 5 2 = 2 5 - 5

2 5 - 5 2

使用根式运算法则:

a a = a

22 = 2

= 2 5 - 5

= \frac{2 ( 5 + 1 )}{2 5 - 5}

乘以共轭根式

\frac{5 - 5}{5 - 5}

= \frac{2 ( 5 + 1 ) 5 - 5}{2 5 - 5 5 - 5}

2 5 - 5 5 - 5 = 10 - 25

2 5 - 5 5 - 5

使用根式运算法则:

a a = a

5 - 5 5 - 5 = 5 - 5

= 2 (5 - 5)

使用分配律:

a (b - c) = ab - a c

a = 2, b = 5, c = 5

= 2 \cdot 5 - 25

数字相乘:

2 \cdot 5 = 10

= 10 - 25

= \frac{2 ( 5 + 1 ) 5 - 5}{10 - 2 5}

因式分解出通项

- 2 : - 2 (5 - 5)

- 25 + 10

将

10

改写为

2 \cdot 5

= - 25 + 2 \cdot 5

因式分解出通项

- 2

= - 2 (5 - 5)

= - \frac{2 ( 5 + 1 ) 5 - 5}{2 ( 5 - 5 )}

消掉

- \frac{2 ( 5 + 1 ) 5 - 5}{2 ( 5 - 5 )} : \frac{2 ( 5 + 1 ) 5 - 5}{2 ( 5 - 5 )}

- \frac{2 ( 5 + 1 ) 5 - 5}{2 ( 5 - 5 )}

5 - 5 = - (5 - 5)

= - \frac{2 ( 1 + 5 ) 5 - 5}{- 2 ( 5 - 5 )}

整理后得

= \frac{2 ( 5 + 1 ) 5 - 5}{2 ( 5 - 5 )}

= \frac{2 ( 5 + 1 ) 5 - 5}{2 ( 5 - 5 )}

乘以共轭根式

\frac{5 + 5}{5 + 5}

= \frac{2 ( 5 + 1 ) 5 - 5 ( 5 + 5 )}{2 ( 5 - 5 ) ( 5 + 5 )}

2 (5 + 1) 5 - 5 (5 + 5) = 610 5 - 5 + 102 5 - 5

2 (5 + 1) 5 - 5 (5 + 5)

= 2 (5 + 1) (5 + 5) 5 - 5

乘开

(5 + 1) (5 + 5) : 65 + 10

(5 + 1) (5 + 5)

使用 FOIL 方法:

(a + b) (c + d) = a c + a d + b c + b d

a = 5, b = 1, c = 5, d = 5

= 5 \cdot 5 + 55 + 1 \cdot 5 + 1 \cdot 5

= 55 + 55 + 1 \cdot 5 + 1 \cdot 5

化简

55 + 55 + 1 \cdot 5 + 1 \cdot 5 : 65 + 10

55 + 55 + 1 \cdot 5 + 1 \cdot 5

同类项相加:

55 + 1 \cdot 5 = 65

= 65 + 55 + 1 \cdot 5

使用根式运算法则:

a a = a

55 = 5

= 65 + 5 + 1 \cdot 5

数字相乘:

1 \cdot 5 = 5

= 65 + 5 + 5

数字相加:

5 + 5 = 10

= 65 + 10

= 65 + 10

= 2 5 - 5 (65 + 10)

乘开

2 5 - 5 (65 + 10) : 610 5 - 5 + 102 5 - 5

2 5 - 5 (65 + 10)

使用分配律:

a (b + c) = ab + a c

a = 2 5 - 5, b = 65, c = 10

= 2 5 - 5 \cdot 65 + 2 5 - 5 \cdot 10

= 625 5 - 5 + 102 5 - 5

625 5 - 5 = 610 5 - 5

625 5 - 5

使用根式运算法则:

a b = a \cdot b

25 5 - 5 = 2 \cdot 5 (5 - 5)

= 6 2 \cdot 5 (5 - 5)

数字相乘:

2 \cdot 5 = 10

= 6 10 (5 - 5)

使用根式运算法则:

n ab = n a n b,

假定

a \geq 0, b \geq 0

10 (5 - 5) = 10 5 - 5

= 610 5 - 5

= 610 5 - 5 + 102 5 - 5

= 610 5 - 5 + 102 5 - 5

2 (5 - 5) (5 + 5) = 40

2 (5 - 5) (5 + 5)

乘开

(5 - 5) (5 + 5) : 20

(5 - 5) (5 + 5)

使用平方差公式:

(a - b) (a + b) = a^{2} - b^{2}

a = 5, b = 5

= 5^{2} - (5)^{2}

化简

5^{2} - (5)^{2} : 20

5^{2} - (5)^{2}

5^{2} = 25

5^{2}

5^{2} = 25

= 25

(5)^{2} = 5

(5)^{2}

使用根式运算法则:

a = a^{\frac{1}{2}}

= (5^{\frac{1}{2}})^{2}

使用指数法则:

(a^{b})^{c} = a^{b c}

= 5^{\frac{1}{2} \cdot 2}

\frac{1}{2} \cdot 2 = 1

\frac{1}{2} \cdot 2

分式相乘:

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

= \frac{1 \cdot 2}{2}

约分:

2

= 1

= 5

= 25 - 5

数字相减:

25 - 5 = 20

= 20

= 20

= 2 \cdot 20

乘开

2 \cdot 20 : 40

2 \cdot 20

打开括号

= 2 \cdot 20

数字相乘:

2 \cdot 20 = 40

= 40

= 40

= \frac{6 10 5 - 5 + 10 2 5 - 5}{40}

分解

610 5 - 5 + 102 5 - 5 : 2 5 - 5 (310 + 52)

610 5 - 5 + 102 5 - 5

改写为

= 3 \cdot 2 5 - 5 10 + 5 \cdot 2 5 - 5 2

因式分解出通项

2 5 - 5

= 2 5 - 5 (310 + 52)

= \frac{2 5 - 5 ( 3 10 + 5 2 )}{40}

约分:

2

= \frac{( 3 10 + 5 2 ) 5 - 5}{20}

= \frac{( 3 10 + 5 2 ) 5 - 5}{20}

= \frac{( 3 10 + 5 2 ) 5 - 5}{20}

流行的例子

cos (157. 5^{\circ})

tan(arccos(-4/5))

tan (arccos (- \frac{4}{5}))

sin (\frac{- π}{3})

sin (\frac{- π}{6})

\frac{sin ( π )}{2}