zs

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

受欢迎的三角函数 >

1/(cos(x))=3

解答

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

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

在两边乘以

cos (x)

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

在两边乘以

cos (x)

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

化简

1 = 3 cos (x)

1 = 3 cos (x)

交换两边

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}

验证解

找到无定义的点（奇点）:

cos (x) = 0

取

\frac{1}{cos ( x )}

的分母，令其等于零

cos (x) = 0

以下点无定义

cos (x) = 0

将不在定义域的点与解相综合:

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

2sin(x)cos(x)=(sqrt(3))/2

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

sin(2θ)=-(2sqrt(6))/7 ,pi<= θ<= (3pi)/2

sin (2 θ) = - \frac{2 6}{7}, π \leq θ \leq \frac{3 π}{2}

cos(2t)=(sqrt(3))/2

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

cos(x)=-0.3178,0<= x<= 2pi

cos (x) = - 0.3178, 0 \leq x \leq 2 π

arccos(x)= pi/3

arccos (x) = \frac{π}{3}