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受欢迎的三角函数 >

3cos(x)+6=cos(x)+5

解答

3 cos (x) + 6 = cos (x) + 5

解答

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

+1

度数

x = 12 0^{\circ} + 36 0^{\circ} n, x = 24 0^{\circ} + 36 0^{\circ} n

求解步骤

3 cos (x) + 6 = cos (x) + 5

用替代法求解

3 cos (x) + 6 = cos (x) + 5

令

: cos (x) = u

3 u + 6 = u + 5

3 u + 6 = u + 5 : u = - \frac{1}{2}

3 u + 6 = u + 5

将

6

到右边

3 u + 6 = u + 5

两边减去

6

3 u + 6 - 6 = u + 5 - 6

化简

3 u = u - 1

3 u = u - 1

将

u

para o lado esquerdo

3 u = u - 1

两边减去

u

3 u - u = u - 1 - u

化简

2 u = - 1

2 u = - 1

两边除以

2

2 u = - 1

两边除以

2

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

化简

u = - \frac{1}{2}

u = - \frac{1}{2}

u = cos (x)

代回

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

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

cos (x) = - \frac{1}{2} : x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

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

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

的通解

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}

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

合并所有解

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

作图

流行的例子

cos(x)= 1/3 ,(3pi)/2 <x<2pi

cos (x) = \frac{1}{3}, \frac{3 π}{2} < x < 2 π

(2.68)/(sin(126))=(1.2)/(sin(x))

\frac{2.68}{sin ( 12 6 ^{\circ} )} = \frac{1.2}{sin ( x )}

3csc^2(x)-5csc(x)-2=0

3 csc^{2} (x) - 5 csc (x) - 2 = 0

((sin(5x)))/((-1cos(5x)))=0

\frac{( sin ( 5 x ) )}{( - 1 cos ( 5 x ) )} = 0

sin (x) = cos (4 0^{\circ})