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受欢迎的三角函数 >

2sin(x-60)=cos(x-30)

解答

2 sin (x - 6 0^{\circ}) = cos (x - 3 0^{\circ})

解答

x = 1.38067 \dots + 18 0^{\circ} n

+1

弧度

x = 1.38067 \dots + πn

求解步骤

2 sin (x - 6 0^{\circ}) = cos (x - 3 0^{\circ})

使用三角恒等式改写

2 sin (x - 6 0^{\circ}) = cos (x - 3 0^{\circ})

使用三角恒等式改写

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

使用角差恒等式:

sin (s - t) = sin (s) cos (t) - cos (s) sin (t)

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

化简

sin (x) cos (6 0^{\circ}) - cos (x) sin (6 0^{\circ}) : \frac{1}{2} sin (x) - \frac{3}{2} cos (x)

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

化简

cos (6 0^{\circ}) : \frac{1}{2}

cos (6 0^{\circ})

使用以下普通恒等式:

cos (6 0^{\circ}) = \frac{1}{2}

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{1}{2}

= \frac{1}{2} sin (x) - sin (6 0^{\circ}) cos (x)

化简

sin (6 0^{\circ}) : \frac{3}{2}

sin (6 0^{\circ})

使用以下普通恒等式:

sin (6 0^{\circ}) = \frac{3}{2}

sin (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} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{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} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

= \frac{3}{2}

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

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

使用角差恒等式:

cos (s - t) = cos (s) cos (t) + sin (s) sin (t)

= cos (x) cos (3 0^{\circ}) + sin (x) sin (3 0^{\circ})

化简

cos (x) cos (3 0^{\circ}) + sin (x) sin (3 0^{\circ}) : \frac{3}{2} cos (x) + \frac{1}{2} sin (x)

cos (x) cos (3 0^{\circ}) + sin (x) sin (3 0^{\circ})

化简

cos (3 0^{\circ}) : \frac{3}{2}

cos (3 0^{\circ})

使用以下普通恒等式:

cos (3 0^{\circ}) = \frac{3}{2}

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{3}{2}

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

化简

sin (3 0^{\circ}) : \frac{1}{2}

sin (3 0^{\circ})

使用以下普通恒等式:

sin (3 0^{\circ}) = \frac{1}{2}

sin (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} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{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} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

= \frac{1}{2}

= \frac{3}{2} cos (x) + \frac{1}{2} sin (x)

= \frac{3}{2} cos (x) + \frac{1}{2} sin (x)

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

化简

2 (\frac{1}{2} sin (x) - \frac{3}{2} cos (x)) : sin (x) - 3 cos (x)

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

使用分配律:

a (b - c) = ab - a c

a = 2, b = \frac{1}{2} sin (x), c = \frac{3}{2} cos (x)

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

化简

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

2 \cdot \frac{1}{2} sin (x) - 2 \cdot \frac{3}{2} cos (x)

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

2 \cdot \frac{1}{2} sin (x)

分式相乘:

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

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

约分:

2

= sin (x) \cdot 1

乘以:

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

= sin (x)

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

2 \cdot \frac{3}{2} cos (x)

分式相乘:

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

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

约分:

2

= cos (x) 3

= sin (x) - 3 cos (x)

= sin (x) - 3 cos (x)

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

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

两边减去

\frac{3}{2} cos (x) + \frac{1}{2} sin (x)

\frac{1}{2} sin (x) - \frac{3}{2} cos (x) - 3 cos (x) = 0

化简

\frac{1}{2} sin (x) - \frac{3}{2} cos (x) - 3 cos (x) : \frac{sin ( x ) - 3 3 cos ( x )}{2}

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

\frac{1}{2} sin (x) = \frac{sin ( x )}{2}

\frac{1}{2} sin (x)

分式相乘:

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

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

乘以:

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

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

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

\frac{3}{2} cos (x)

分式相乘:

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

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

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

合并分式

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

使用法则

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

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

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

将项转换为分式:

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

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

同类项相加:

- 3 cos (x) - 23 cos (x) = - 33 cos (x)

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

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

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

sin (x) - 33 cos (x) = 0

使用三角恒等式改写

sin (x) - 33 cos (x) = 0

在两边除以

cos (x), cos (x) \neq = 0

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

化简

\frac{sin ( x )}{cos ( x )} - 33 = 0

使用基本三角恒等式:

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

tan (x) - 33 = 0

tan (x) - 33 = 0

将

33

到右边

tan (x) - 33 = 0

两边加上

33

tan (x) - 33 + 33 = 0 + 33

化简

tan (x) = 33

tan (x) = 33

使用反三角函数性质

tan (x) = 33

tan (x) = 33

的通解

tan (x) = a \Rightarrow x = arctan (a) + 18 0^{\circ} n

x = arctan (33) + 18 0^{\circ} n

x = arctan (33) + 18 0^{\circ} n

以小数形式表示解

x = 1.38067 \dots + 18 0^{\circ} n

作图

流行的例子

sin(x)=sin(pi/2-x)

sin (x) = sin (\frac{π}{2} - x)

cos (θ) = - \frac{24}{25}

sin(x-30)=cos(2x)

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

sin (x) = sec (x)

sin(x-pi/3)=0.4

sin (x - \frac{π}{3}) = 0.4