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受欢迎的三角函数 >

sec(x)tan(x)=2sqrt(3)

解答

sec (x) tan (x) = 23

解答

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

+1

度数

x = 6 0^{\circ} + 36 0^{\circ} n, x = 12 0^{\circ} + 36 0^{\circ} n

求解步骤

sec (x) tan (x) = 23

两边减去

23

sec (x) tan (x) - 23 = 0

用 sin, cos 表示

- 23 + sec (x) tan (x)

使用基本三角恒等式:

sec (x) = \frac{1}{cos ( x )}

= - 23 + \frac{1}{cos ( x )} tan (x)

使用基本三角恒等式:

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

= - 23 + \frac{1}{cos ( x )} \cdot \frac{sin ( x )}{cos ( x )}

化简

- 23 + \frac{1}{cos ( x )} \cdot \frac{sin ( x )}{cos ( x )} : \frac{- 2 3 cos ^{2} ( x ) + sin ( x )}{cos ^{2} ( x )}

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

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

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

分式相乘:

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

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

乘以:

1 \cdot sin (x) = sin (x)

= \frac{sin ( 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)

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

= - 23 + \frac{sin ( x )}{cos ^{2} ( x )}

将项转换为分式:

23 = \frac{2 \cdot 3 cos ^{2} ( x )}{cos ^{2} ( x )}

= - \frac{2 3 cos ^{2} ( x )}{cos ^{2} ( x )} + \frac{sin ( x )}{cos ^{2} ( 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{- 2 3 cos ^{2} ( x ) + sin ( x )}{cos ^{2} ( x )}

= \frac{- 2 3 cos ^{2} ( x ) + sin ( x )}{cos ^{2} ( x )}

\frac{sin ( x ) - 2 cos ^{2} ( x ) 3}{cos ^{2} ( x )} = 0

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

sin (x) - 2 cos^{2} (x) 3 = 0

使用三角恒等式改写

sin (x) - 2 cos^{2} (x) 3

使用毕达哥拉斯恒等式:

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

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

= sin (x) - 2 (1 - sin^{2} (x)) 3

sin (x) - (1 - sin^{2} (x)) \cdot 23 = 0

用替代法求解

sin (x) - (1 - sin^{2} (x)) \cdot 23 = 0

令

: sin (x) = u

u - (1 - u^{2}) \cdot 23 = 0

u - (1 - u^{2}) \cdot 23 = 0 : u = \frac{3}{2}, u = - \frac{2 3}{3}

u - (1 - u^{2}) \cdot 23 = 0

展开

u - (1 - u^{2}) \cdot 23 : u - 23 + 23 u^{2}

u - (1 - u^{2}) \cdot 23

= u - 23 (1 - u^{2})

乘开

- 23 (1 - u^{2}) : - 23 + 23 u^{2}

- 23 (1 - u^{2})

使用分配律:

a (b - c) = ab - a c

a = - 23, b = 1, c = u^{2}

= - 23 \cdot 1 - (- 23) u^{2}

使用加减运算法则

- (- a) = a

= - 2 \cdot 1 \cdot 3 + 23 u^{2}

数字相乘:

2 \cdot 1 = 2

= - 23 + 23 u^{2}

= u - 23 + 23 u^{2}

u - 23 + 23 u^{2} = 0

改写成标准形式

a x^{2} + b x + c = 0

23 u^{2} + u - 23 = 0

使用求根公式求解

23 u^{2} + u - 23 = 0

二次方程求根公式:

若

a = 23, b = 1, c = - 23

u_{1, 2} = \frac{- 1 \pm 1 ^{2} - 4 \cdot 2 3 ( - 2 3 )}{2 \cdot 2 3}

u_{1, 2} = \frac{- 1 \pm 1 ^{2} - 4 \cdot 2 3 ( - 2 3 )}{2 \cdot 2 3}

1^{2} - 4 \cdot 23 (- 23) = 7

1^{2} - 4 \cdot 23 (- 23)

使用法则

1^{a} = 1

1^{2} = 1

= 1 - 4 \cdot 23 (- 23)

使用法则

- (- a) = a

= 1 + 4 \cdot 23 \cdot 23

4 \cdot 23 \cdot 23 = 48

4 \cdot 23 \cdot 23

数字相乘:

4 \cdot 2 \cdot 2 = 16

= 1633

使用根式运算法则:

a a = a

33 = 3

= 16 \cdot 3

数字相乘:

16 \cdot 3 = 48

= 48

= 1 + 48

数字相加:

1 + 48 = 49

= 49

因式分解数字:

49 = 7^{2}

= 7^{2}

使用根式运算法则:

n a^{n} = a

7^{2} = 7

= 7

u_{1, 2} = \frac{- 1 \pm 7}{2 \cdot 2 3}

将解分隔开

u_{1} = \frac{- 1 + 7}{2 \cdot 2 3}, u_{2} = \frac{- 1 - 7}{2 \cdot 2 3}

u = \frac{- 1 + 7}{2 \cdot 2 3} : \frac{3}{2}

\frac{- 1 + 7}{2 \cdot 2 3}

数字相加/相减:

- 1 + 7 = 6

= \frac{6}{2 \cdot 2 3}

数字相乘:

2 \cdot 2 = 4

= \frac{6}{4 3}

约分:

2

= \frac{3}{2 3}

使用根式运算法则:

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

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

= \frac{3}{2 \cdot 3 ^{\frac{1}{2}}}

使用指数法则:

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

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

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

数字相减:

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

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

使用根式运算法则:

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

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

= \frac{3}{2}

u = \frac{- 1 - 7}{2 \cdot 2 3} : - \frac{2 3}{3}

\frac{- 1 - 7}{2 \cdot 2 3}

数字相减:

- 1 - 7 = - 8

= \frac{- 8}{2 \cdot 2 3}

数字相乘:

2 \cdot 2 = 4

= \frac{- 8}{4 3}

使用分式法则:

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

= - \frac{8}{4 3}

数字相除:

\frac{8}{4} = 2

= - \frac{2}{3}

- \frac{2}{3}

有理化:

- \frac{2 3}{3}

- \frac{2}{3}

乘以共轭根式

\frac{3}{3}

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

33 = 3

33

使用根式运算法则:

a a = a

33 = 3

= 3

= - \frac{2 3}{3}

= - \frac{2 3}{3}

二次方程组的解是:

u = \frac{3}{2}, u = - \frac{2 3}{3}

u = sin (x)

代回

sin (x) = \frac{3}{2}, sin (x) = - \frac{2 3}{3}

sin (x) = \frac{3}{2}, sin (x) = - \frac{2 3}{3}

sin (x) = \frac{3}{2} : x = \frac{π}{3} + 2 πn, x = \frac{2 π}{3} + 2 πn

sin (x) = \frac{3}{2}

sin (x) = \frac{3}{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}

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

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

sin (x) = - \frac{2 3}{3} :

无解

sin (x) = - \frac{2 3}{3}

- 1 \leq sin (x) \leq 1

无解

合并所有解

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

作图

流行的例子

cos (2 x + 6 0^{\circ}) = 0

cos (θ) = 0.6596

-1=tan(x+pi/(18))

- 1 = tan (x + \frac{π}{18})

cos(x+60)=-sin(x)

cos (x + 6 0^{\circ}) = - sin (x)

sin(40+x)=cos(5x+10)

sin (4 0^{\circ} + x) = cos (5 x + 10)