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受欢迎的三角函数 >

(1-cos(45))/(1+cos(45))

解答

\frac{1 - cos ( 4 5 ^{\circ} )}{1 + cos ( 4 5 ^{\circ} )}

解答

3 - 22

+1

十进制

0.17157 \dots

求解步骤

\frac{1 - cos ( 4 5 ^{\circ} )}{1 + cos ( 4 5 ^{\circ} )}

使用以下普通恒等式:

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

cos (4 5^{\circ})

cos (x)

周期表（周期为

36 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} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x 18 0^{\circ} 21 0^{\circ} 22 5^{\circ} 24 0^{\circ} 27 0^{\circ} 30 0^{\circ} 31 5^{\circ} 33 0^{\circ} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

= \frac{2}{2}

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

化简

\frac{1 - \frac{2}{2}}{1 + \frac{2}{2}} : 3 - 22

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

化简

1 + \frac{2}{2} : \frac{2 + 1}{2}

1 + \frac{2}{2}

将项转换为分式:

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

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

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 2 + 2}{2}

数字相乘:

1 \cdot 2 = 2

= \frac{2 + 2}{2}

分解

2 + 2 : 2 (2 + 1)

2 + 2

2 = 22

= 22 + 2

因式分解出通项

2

= 2 (2 + 1)

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

消掉

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

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

使用根式运算法则:

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

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

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

使用指数法则:

\frac{x ^{a}}{x ^{b}} = \frac{1}{x ^{b - a}}

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

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

数字相减:

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

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

使用根式运算法则:

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

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

= \frac{2 + 1}{2}

= \frac{2 + 1}{2}

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

化简

1 - \frac{2}{2} : \frac{2 - 1}{2}

1 - \frac{2}{2}

将项转换为分式:

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

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

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 2 - 2}{2}

数字相乘:

1 \cdot 2 = 2

= \frac{2 - 2}{2}

分解

2 - 2 : 2 (2 - 1)

2 - 2

2 = 22

= 22 - 2

因式分解出通项

2

= 2 (2 - 1)

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

消掉

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

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

使用根式运算法则:

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

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

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

使用指数法则:

\frac{x ^{a}}{x ^{b}} = \frac{1}{x ^{b - a}}

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

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

数字相减:

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

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

使用根式运算法则:

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

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

= \frac{2 - 1}{2}

= \frac{2 - 1}{2}

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

分式相除:

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

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

约分:

2

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

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

有理化:

3 - 22

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

乘以共轭根式

\frac{2 - 1}{2 - 1}

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

(2 - 1) (2 - 1) = 3 - 22

(2 - 1) (2 - 1)

使用指数法则:

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

(2 - 1) (2 - 1) = (2 - 1)^{1 + 1}

= (2 - 1)^{1 + 1}

数字相加:

1 + 1 = 2

= (2 - 1)^{2}

使用完全平方公式:

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

a = 2, b = 1

= (2)^{2} - 22 \cdot 1 + 1^{2}

化简

(2)^{2} - 22 \cdot 1 + 1^{2} : 3 - 22

(2)^{2} - 22 \cdot 1 + 1^{2}

使用法则

1^{a} = 1

1^{2} = 1

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

(2)^{2} = 2

(2)^{2}

使用根式运算法则:

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

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

使用指数法则:

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

= 2^{\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

= 2

22 \cdot 1 = 22

22 \cdot 1

数字相乘:

2 \cdot 1 = 2

= 22

= 2 - 22 + 1

数字相加:

2 + 1 = 3

= 3 - 22

= 3 - 22

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

(2 + 1) (2 - 1)

使用平方差公式:

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

a = 2, b = 1

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

化简

(2)^{2} - 1^{2} : 1

(2)^{2} - 1^{2}

使用法则

1^{a} = 1

1^{2} = 1

= (2)^{2} - 1

(2)^{2} = 2

(2)^{2}

使用根式运算法则:

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

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

使用指数法则:

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

= 2^{\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

= 2

= 2 - 1

数字相减:

2 - 1 = 1

= 1

= 1

= \frac{3 - 2 2}{1}

使用法则

\frac{a}{1} = a

= 3 - 22

= 3 - 22

= 3 - 22

流行的例子

e^{2} sin (0)

sin(arcsin(pi/3))

sin (arcsin (\frac{π}{3}))

6 sin (2 0^{\circ})

cos (3 0^{\circ}) \cdot 4

120 cos (1 5^{\circ})