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受欢迎的三角函数 >

1/(sin(x)cos(x))=2sqrt(2)

解答

\frac{1}{sin ( x ) cos ( x )} = 22

解答

x = \frac{π}{8} + πn, x = \frac{3 π}{8} + πn

+1

度数

x = 22. 5^{\circ} + 18 0^{\circ} n, x = 67. 5^{\circ} + 18 0^{\circ} n

求解步骤

\frac{1}{sin ( x ) cos ( x )} = 22

使用三角恒等式改写

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

使用倍角公式:

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

sin (x) cos (x) = \frac{sin ( 2 x )}{2}

= \frac{1}{\frac{s i n ( 2 x )}{2}}

\frac{1}{\frac{s i n ( 2 x )}{2}} = 22

化简

\frac{1}{\frac{s i n ( 2 x )}{2}} : \frac{2}{sin ( 2 x )}

\frac{1}{\frac{s i n ( 2 x )}{2}}

使用分式法则:

\frac{1}{\frac{b}{c}} = \frac{c}{b}

= \frac{2}{sin ( 2 x )}

\frac{2}{sin ( 2 x )} = 22

在两边乘以

sin (2 x)

\frac{2}{sin ( 2 x )} = 22

在两边乘以

sin (2 x)

\frac{2}{sin ( 2 x )} sin (2 x) = 22 sin (2 x)

化简

2 = 22 sin (2 x)

2 = 22 sin (2 x)

交换两边

22 sin (2 x) = 2

两边除以

22

22 sin (2 x) = 2

两边除以

22

\frac{2 2 sin ( 2 x )}{2 2} = \frac{2}{2 2}

化简

\frac{2 2 sin ( 2 x )}{2 2} = \frac{2}{2 2}

化简

\frac{2 2 sin ( 2 x )}{2 2} : sin (2 x)

\frac{2 2 sin ( 2 x )}{2 2}

数字相除:

\frac{2}{2} = 1

= \frac{2 sin ( 2 x )}{2}

约分:

2

= sin (2 x)

化简

\frac{2}{2 2} : \frac{2}{2}

\frac{2}{2 2}

数字相除:

\frac{2}{2} = 1

= \frac{1}{2}

\frac{1}{2}

有理化:

\frac{2}{2}

\frac{1}{2}

乘以共轭根式

\frac{2}{2}

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

1 \cdot 2 = 2

22 = 2

22

使用根式运算法则:

a a = a

22 = 2

= 2

= \frac{2}{2}

= \frac{2}{2}

sin (2 x) = \frac{2}{2}

sin (2 x) = \frac{2}{2}

sin (2 x) = \frac{2}{2}

验证解

找到无定义的点（奇点）:

sin (2 x) = 0

取

\frac{1}{\frac{s i n ( 2 x )}{2}}

的分母，令其等于零

解

\frac{sin ( 2 x )}{2} = 0 : sin (2 x) = 0

\frac{sin ( 2 x )}{2} = 0

在两边乘以

2

\frac{sin ( 2 x )}{2} = 0

在两边乘以

2

\frac{2 sin ( 2 x )}{2} = 0 \cdot 2

化简

sin (2 x) = 0

sin (2 x) = 0

以下点无定义

sin (2 x) = 0

将不在定义域的点与解相综合:

sin (2 x) = \frac{2}{2}

sin (2 x) = \frac{2}{2}

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}

2 x = \frac{π}{4} + 2 πn, 2 x = \frac{3 π}{4} + 2 πn

2 x = \frac{π}{4} + 2 πn, 2 x = \frac{3 π}{4} + 2 πn

解

2 x = \frac{π}{4} + 2 πn : x = \frac{π}{8} + πn

2 x = \frac{π}{4} + 2 πn

两边除以

2

2 x = \frac{π}{4} + 2 πn

两边除以

2

\frac{2 x}{2} = \frac{\frac{π}{4}}{2} + \frac{2 πn}{2}

化简

\frac{2 x}{2} = \frac{\frac{π}{4}}{2} + \frac{2 πn}{2}

化简

\frac{2 x}{2} : x

\frac{2 x}{2}

数字相除:

\frac{2}{2} = 1

= x

化简

\frac{\frac{π}{4}}{2} + \frac{2 πn}{2} : \frac{π}{8} + πn

\frac{\frac{π}{4}}{2} + \frac{2 πn}{2}

\frac{\frac{π}{4}}{2} = \frac{π}{8}

\frac{\frac{π}{4}}{2}

使用分式法则:

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

= \frac{π}{4 \cdot 2}

数字相乘:

4 \cdot 2 = 8

= \frac{π}{8}

\frac{2 πn}{2} = πn

\frac{2 πn}{2}

数字相除:

\frac{2}{2} = 1

= πn

= \frac{π}{8} + πn

x = \frac{π}{8} + πn

x = \frac{π}{8} + πn

x = \frac{π}{8} + πn

解

2 x = \frac{3 π}{4} + 2 πn : x = \frac{3 π}{8} + πn

2 x = \frac{3 π}{4} + 2 πn

两边除以

2

2 x = \frac{3 π}{4} + 2 πn

两边除以

2

\frac{2 x}{2} = \frac{\frac{3 π}{4}}{2} + \frac{2 πn}{2}

化简

\frac{2 x}{2} = \frac{\frac{3 π}{4}}{2} + \frac{2 πn}{2}

化简

\frac{2 x}{2} : x

\frac{2 x}{2}

数字相除:

\frac{2}{2} = 1

= x

化简

\frac{\frac{3 π}{4}}{2} + \frac{2 πn}{2} : \frac{3 π}{8} + πn

\frac{\frac{3 π}{4}}{2} + \frac{2 πn}{2}

\frac{\frac{3 π}{4}}{2} = \frac{3 π}{8}

\frac{\frac{3 π}{4}}{2}

使用分式法则:

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

= \frac{3 π}{4 \cdot 2}

数字相乘:

4 \cdot 2 = 8

= \frac{3 π}{8}

\frac{2 πn}{2} = πn

\frac{2 πn}{2}

数字相除:

\frac{2}{2} = 1

= πn

= \frac{3 π}{8} + πn

x = \frac{3 π}{8} + πn

x = \frac{3 π}{8} + πn

x = \frac{3 π}{8} + πn

x = \frac{π}{8} + πn, x = \frac{3 π}{8} + πn

作图

流行的例子

tan(x)= 1/(5^{1/2)}

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

sqrt(3)csc(x/2)-2=0

3 csc (\frac{x}{2}) - 2 = 0

arcsin(y)= 1/(sqrt(2))

arcsin (y) = \frac{1}{2}

6 sin (y) = 0

tan(θ)=-(sqrt(3))/3 ,0<= θ<= 2pi

tan (θ) = - \frac{3}{3}, 0 \leq θ \leq 2 π