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受欢迎的三角函数 >

3/(cot(x))=8-5tan(x)

解答

\frac{3}{cot ( x )} = 8 - 5 tan (x)

解答

x = \frac{π}{4} + πn

+1

度数

x = 4 5^{\circ} + 18 0^{\circ} n

求解步骤

\frac{3}{cot ( x )} = 8 - 5 tan (x)

两边减去

8 - 5 tan (x)

\frac{3}{cot ( x )} - 8 + 5 tan (x) = 0

化简

\frac{3}{cot ( x )} - 8 + 5 tan (x) : \frac{3 - 8 cot ( x ) + 5 tan ( x ) cot ( x )}{cot ( x )}

\frac{3}{cot ( x )} - 8 + 5 tan (x)

将项转换为分式:

8 = \frac{8 cot ( x )}{cot ( x )}, 5 tan (x) = \frac{5 tan ( x ) cot ( x )}{cot ( x )}

= \frac{3}{cot ( x )} - \frac{8 cot ( x )}{cot ( x )} + \frac{5 tan ( x ) cot ( x )}{cot ( 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{3 - 8 cot ( x ) + 5 tan ( x ) cot ( x )}{cot ( x )}

\frac{3 - 8 cot ( x ) + 5 tan ( x ) cot ( x )}{cot ( x )} = 0

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

3 - 8 cot (x) + 5 tan (x) cot (x) = 0

使用三角恒等式改写

3 - 8 cot (x) + 5 cot (x) tan (x)

使用基本三角恒等式:

tan (x) = \frac{1}{cot ( x )}

= 3 - 8 cot (x) + 5 cot (x) \frac{1}{cot ( x )}

化简

3 - 8 cot (x) + 5 cot (x) \frac{1}{cot ( x )} : - 8 cot (x) + 8

3 - 8 cot (x) + 5 cot (x) \frac{1}{cot ( x )}

5 cot (x) \frac{1}{cot ( x )} = 5

5 cot (x) \frac{1}{cot ( x )}

分式相乘:

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

= \frac{1 \cdot 5 cot ( x )}{cot ( x )}

约分:

cot (x)

= 1 \cdot 5

数字相乘:

1 \cdot 5 = 5

= 5

= 3 - 8 cot (x) + 5

对同类项分组

= - 8 cot (x) + 3 + 5

数字相加:

3 + 5 = 8

= - 8 cot (x) + 8

= - 8 cot (x) + 8

8 - 8 cot (x) = 0

将

8

到右边

8 - 8 cot (x) = 0

两边减去

8

8 - 8 cot (x) - 8 = 0 - 8

化简

- 8 cot (x) = - 8

- 8 cot (x) = - 8

两边除以

- 8

- 8 cot (x) = - 8

两边除以

- 8

\frac{- 8 cot ( x )}{- 8} = \frac{- 8}{- 8}

化简

cot (x) = 1

cot (x) = 1

cot (x) = 1

的通解

cot (x)

周期表（周期为

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} cot (x) \mp \infty 31 \frac{3}{3} 0 - \frac{3}{3} - 1 - 3

x = \frac{π}{4} + πn

x = \frac{π}{4} + πn

作图

流行的例子

sin(θ)= 3/8 ,sin(2θ)

sin (θ) = \frac{3}{8}, sin (2 θ)

2(1-cos^2(x))= 3/2

2 (1 - cos^{2} (x)) = \frac{3}{2}

cos(3θ)=-(sqrt(2))/2

cos (3 θ) = - \frac{2}{2}

25*sin(x)-1.5*cos(x)=20

25 \cdot sin (x) - 1.5 \cdot cos (x) = 20

3cos(3x)=2cos(x)

3 cos (3 x) = 2 cos (x)