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受欢迎的三角函数 >

2cos(x)= 6/7

解答

2 cos (x) = \frac{6}{7}

解答

x = 1.12788 \dots + 2 πn, x = 2 π - 1.12788 \dots + 2 πn

+1

度数

x = 64.62306 \dots^{\circ} + 36 0^{\circ} n, x = 295.37693 \dots^{\circ} + 36 0^{\circ} n

求解步骤

2 cos (x) = \frac{6}{7}

两边除以

2

2 cos (x) = \frac{6}{7}

两边除以

2

\frac{2 cos ( x )}{2} = \frac{\frac{6}{7}}{2}

化简

\frac{2 cos ( x )}{2} = \frac{\frac{6}{7}}{2}

化简

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

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

数字相除:

\frac{2}{2} = 1

= cos (x)

化简

\frac{\frac{6}{7}}{2} : \frac{3}{7}

\frac{\frac{6}{7}}{2}

使用分式法则:

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

= \frac{6}{7 \cdot 2}

数字相乘:

7 \cdot 2 = 14

= \frac{6}{14}

约分:

2

= \frac{3}{7}

cos (x) = \frac{3}{7}

cos (x) = \frac{3}{7}

cos (x) = \frac{3}{7}

使用反三角函数性质

cos (x) = \frac{3}{7}

cos (x) = \frac{3}{7}

的通解

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

x = arccos (\frac{3}{7}) + 2 πn, x = 2 π - arccos (\frac{3}{7}) + 2 πn

x = arccos (\frac{3}{7}) + 2 πn, x = 2 π - arccos (\frac{3}{7}) + 2 πn

以小数形式表示解

x = 1.12788 \dots + 2 πn, x = 2 π - 1.12788 \dots + 2 πn

作图

流行的例子

tan(θ)= 1/2 ,pi<θ<(3pi)/2

tan (θ) = \frac{1}{2}, π < θ < \frac{3 π}{2}

7/2 =3sin(b(pi/2))+2

\frac{7}{2} = 3 sin (b (\frac{π}{2})) + 2

cos (x) = \frac{2}{8}

solvefor y,x=4sin(2y)

so l v e f or y, x = 4 sin (2 y)

cos^2(x)-5/2 cos(x)-3/2 =0

cos^{2} (x) - \frac{5}{2} cos (x) - \frac{3}{2} = 0