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受欢迎的三角函数 >

0.08=0.12cos^2(3.922t)

解答

0.08 = 0.12 cos^{2} (3.922 t)

解答

t = \frac{0.61547 \dots}{3.922} + \frac{2 πn}{3.922}, t = \frac{2 π}{3.922} - \frac{0.61547 \dots}{3.922} + \frac{2 πn}{3.922}, t = \frac{2.52611 \dots}{3.922} + \frac{2 πn}{3.922}, t = - \frac{2.52611 \dots}{3.922} + \frac{2 πn}{3.922}

+1

度数

t = 8.99143 \dots^{\circ} + 91.78990 \dots^{\circ} n, t = 82.79847 \dots^{\circ} + 91.78990 \dots^{\circ} n, t = 36.90352 \dots^{\circ} + 91.78990 \dots^{\circ} n, t = - 36.90352 \dots^{\circ} + 91.78990 \dots^{\circ} n

求解步骤

0.08 = 0.12 cos^{2} (3.922 t)

交换两边

0.12 cos^{2} (3.922 t) = 0.08

用替代法求解

0.12 cos^{2} (3.922 t) = 0.08

令

: cos (3.922 t) = u

0.12 u^{2} = 0.08

0.12 u^{2} = 0.08 : u = \frac{2}{3}, u = - \frac{2}{3}

0.12 u^{2} = 0.08

在两边乘以

100

0.12 u^{2} = 0.08

To eliminate decimal points, multiply by 10 for every digit after the decimal pointThere are

2

digits to the right of the decimal point, therefore multiply by

100

0.12 u^{2} \cdot 100 = 0.08 \cdot 100

整理后得

12 u^{2} = 8

12 u^{2} = 8

两边除以

12

12 u^{2} = 8

两边除以

12

\frac{12 u ^{2}}{12} = \frac{8}{12}

化简

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

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

对于

x^{2} = f (a)

解为

x = f (a), - f (a)

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

u = cos (3.922 t)

代回

cos (3.922 t) = \frac{2}{3}, cos (3.922 t) = - \frac{2}{3}

cos (3.922 t) = \frac{2}{3}, cos (3.922 t) = - \frac{2}{3}

cos (3.922 t) = \frac{2}{3} : t = \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}, t = \frac{2 π}{3.922} - \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

cos (3.922 t) = \frac{2}{3}

使用反三角函数性质

cos (3.922 t) = \frac{2}{3}

cos (3.922 t) = \frac{2}{3}

的通解

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

3.922 t = arccos (\frac{2}{3}) + 2 πn, 3.922 t = 2 π - arccos (\frac{2}{3}) + 2 πn

3.922 t = arccos (\frac{2}{3}) + 2 πn, 3.922 t = 2 π - arccos (\frac{2}{3}) + 2 πn

解

3.922 t = arccos (\frac{2}{3}) + 2 πn : t = \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

3.922 t = arccos (\frac{2}{3}) + 2 πn

两边除以

3.922

3.922 t = arccos (\frac{2}{3}) + 2 πn

两边除以

3.922

\frac{3.922 t}{3.922} = \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

化简

t = \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

t = \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

解

3.922 t = 2 π - arccos (\frac{2}{3}) + 2 πn : t = \frac{2 π}{3.922} - \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

3.922 t = 2 π - arccos (\frac{2}{3}) + 2 πn

两边除以

3.922

3.922 t = 2 π - arccos (\frac{2}{3}) + 2 πn

两边除以

3.922

\frac{3.922 t}{3.922} = \frac{2 π}{3.922} - \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

化简

t = \frac{2 π}{3.922} - \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

t = \frac{2 π}{3.922} - \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

t = \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}, t = \frac{2 π}{3.922} - \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

cos (3.922 t) = - \frac{2}{3} : t = \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}, t = - \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

cos (3.922 t) = - \frac{2}{3}

使用反三角函数性质

cos (3.922 t) = - \frac{2}{3}

cos (3.922 t) = - \frac{2}{3}

的通解

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

3.922 t = arccos (- \frac{2}{3}) + 2 πn, 3.922 t = - arccos (- \frac{2}{3}) + 2 πn

3.922 t = arccos (- \frac{2}{3}) + 2 πn, 3.922 t = - arccos (- \frac{2}{3}) + 2 πn

解

3.922 t = arccos (- \frac{2}{3}) + 2 πn : t = \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

3.922 t = arccos (- \frac{2}{3}) + 2 πn

两边除以

3.922

3.922 t = arccos (- \frac{2}{3}) + 2 πn

两边除以

3.922

\frac{3.922 t}{3.922} = \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

化简

t = \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

t = \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

解

3.922 t = - arccos (- \frac{2}{3}) + 2 πn : t = - \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

3.922 t = - arccos (- \frac{2}{3}) + 2 πn

两边除以

3.922

3.922 t = - arccos (- \frac{2}{3}) + 2 πn

两边除以

3.922

\frac{3.922 t}{3.922} = - \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

化简

t = - \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

t = - \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

t = \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}, t = - \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

合并所有解

t = \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}, t = \frac{2 π}{3.922} - \frac{arccos ( \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}, t = \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}, t = - \frac{arccos ( - \frac{2}{3} )}{3.922} + \frac{2 πn}{3.922}

以小数形式表示解

t = \frac{0.61547 \dots}{3.922} + \frac{2 πn}{3.922}, t = \frac{2 π}{3.922} - \frac{0.61547 \dots}{3.922} + \frac{2 πn}{3.922}, t = \frac{2.52611 \dots}{3.922} + \frac{2 πn}{3.922}, t = - \frac{2.52611 \dots}{3.922} + \frac{2 πn}{3.922}

作图

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