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受欢迎的三角函数 >

sin(x+pi/3)+cos(x+pi/6)=(sqrt(3))/3

解答

sin (x + \frac{π}{3}) + cos (x + \frac{π}{6}) = \frac{3}{3}

解答

x = 1.23095 \dots + 2 πn, x = 2 π - 1.23095 \dots + 2 πn

+1

度数

x = 70.52877 \dots^{\circ} + 36 0^{\circ} n, x = 289.47122 \dots^{\circ} + 36 0^{\circ} n

求解步骤

sin (x + \frac{π}{3}) + cos (x + \frac{π}{6}) = \frac{3}{3}

使用三角恒等式改写

sin (x + \frac{π}{3}) + cos (x + \frac{π}{6}) = \frac{3}{3}

使用三角恒等式改写

sin (x + \frac{π}{3})

使用角和恒等式:

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

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

化简

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

sin (x) cos (\frac{π}{3}) + cos (x) sin (\frac{π}{3})

化简

cos (\frac{π}{3}) : \frac{1}{2}

cos (\frac{π}{3})

使用以下普通恒等式:

cos (\frac{π}{3}) = \frac{1}{2}

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

化简

sin (\frac{π}{3}) : \frac{3}{2}

sin (\frac{π}{3})

使用以下普通恒等式:

sin (\frac{π}{3}) = \frac{3}{2}

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}

= \frac{3}{2}

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

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

使用角和恒等式:

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

= cos (x) cos (\frac{π}{6}) - sin (x) sin (\frac{π}{6})

化简

cos (x) cos (\frac{π}{6}) - sin (x) sin (\frac{π}{6}) : \frac{3}{2} cos (x) - \frac{1}{2} sin (x)

cos (x) cos (\frac{π}{6}) - sin (x) sin (\frac{π}{6})

化简

cos (\frac{π}{6}) : \frac{3}{2}

cos (\frac{π}{6})

使用以下普通恒等式:

cos (\frac{π}{6}) = \frac{3}{2}

cos (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} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{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} 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 (\frac{π}{6}) sin (x)

化简

sin (\frac{π}{6}) : \frac{1}{2}

sin (\frac{π}{6})

使用以下普通恒等式:

sin (\frac{π}{6}) = \frac{1}{2}

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}

= \frac{1}{2}

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

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

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

化简

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

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

对同类项分组

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

同类项相加:

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

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

因式分解出通项

cos (x)

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

\frac{3}{2} + \frac{3}{2} = 3

\frac{3}{2} + \frac{3}{2}

使用法则

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

= \frac{3 + 3}{2}

分解

3 + 3 : 23

3 + 3

因式分解出通项

3

= 3 (1 + 1)

整理后得

= 23

= \frac{2 3}{2}

数字相除:

\frac{2}{2} = 1

= 3

= 3 cos (x)

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

同类项相加:

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

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

因式分解出通项

sin (x)

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

\frac{1}{2} - \frac{1}{2} = 0

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

整理后得

= 0

= 0

= 3 cos (x)

\frac{3}{3} = \frac{1}{3}

\frac{3}{3}

使用根式运算法则:

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

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

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

使用指数法则:

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

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

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

数字相减:

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

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

使用根式运算法则:

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

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

= \frac{1}{3}

3 cos (x) = \frac{1}{3}

3 cos (x) = \frac{1}{3}

两边减去

\frac{1}{3}

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

化简

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

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

将项转换为分式:

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

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

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 cos ( x ) 3 - 1}{3}

3 cos (x) 3 - 1 = 3 cos (x) - 1

3 cos (x) 3 - 1

使用根式运算法则:

a a = a

33 = 3

= 3 cos (x) - 1

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

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

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

3 cos (x) - 1 = 0

将

1

到右边

3 cos (x) - 1 = 0

两边加上

1

3 cos (x) - 1 + 1 = 0 + 1

化简

3 cos (x) = 1

3 cos (x) = 1

两边除以

3

3 cos (x) = 1

两边除以

3

\frac{3 cos ( x )}{3} = \frac{1}{3}

化简

cos (x) = \frac{1}{3}

cos (x) = \frac{1}{3}

使用反三角函数性质

cos (x) = \frac{1}{3}

cos (x) = \frac{1}{3}

的通解

cos (x) = a \Rightarrow x = arccos (a) + 2 πn, x = 2 π - arccos (a) + 2 πn

x = arccos (\frac{1}{3}) + 2 πn, x = 2 π - arccos (\frac{1}{3}) + 2 πn

x = arccos (\frac{1}{3}) + 2 πn, x = 2 π - arccos (\frac{1}{3}) + 2 πn

以小数形式表示解

x = 1.23095 \dots + 2 πn, x = 2 π - 1.23095 \dots + 2 πn

作图

流行的例子

4sin^2(x)cot(x)-3cot(x)=0

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

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

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

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

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

1=cot^2(x)+csc(x)

1 = cot^{2} (x) + csc (x)

sin(θ/2)=(sqrt(3))/2

sin (\frac{θ}{2}) = \frac{3}{2}