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受欢迎的三角函数 >

3cot^2(x)=9

解答

3 cot^{2} (x) = 9

解答

x = \frac{π}{6} + πn, x = \frac{5 π}{6} + πn

+1

度数

x = 3 0^{\circ} + 18 0^{\circ} n, x = 15 0^{\circ} + 18 0^{\circ} n

求解步骤

3 cot^{2} (x) = 9

用替代法求解

3 cot^{2} (x) = 9

令

: cot (x) = u

3 u^{2} = 9

3 u^{2} = 9 : u = 3, u = - 3

3 u^{2} = 9

两边除以

3

3 u^{2} = 9

两边除以

3

\frac{3 u ^{2}}{3} = \frac{9}{3}

化简

u^{2} = 3

u^{2} = 3

对于

x^{2} = f (a)

解为

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

u = 3, u = - 3

u = cot (x)

代回

cot (x) = 3, cot (x) = - 3

cot (x) = 3, cot (x) = - 3

cot (x) = 3 : x = \frac{π}{6} + πn

cot (x) = 3

cot (x) = 3

的通解

cot (x)

周期表（周期为

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} cot (x) \mp \infty 31 \frac{3}{3} 0 - \frac{3}{3} - 1 - 3

x = \frac{π}{6} + πn

x = \frac{π}{6} + πn

cot (x) = - 3 : x = \frac{5 π}{6} + πn

cot (x) = - 3

cot (x) = - 3

的通解

cot (x)

周期表（周期为

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} cot (x) \mp \infty 31 \frac{3}{3} 0 - \frac{3}{3} - 1 - 3

x = \frac{5 π}{6} + πn

x = \frac{5 π}{6} + πn

合并所有解

x = \frac{π}{6} + πn, x = \frac{5 π}{6} + πn

作图

流行的例子

12^{(2)}=13^{(2)}+5^{(2)}-2(13)(5)cos(B)

1 2^{(2)} = 1 3^{(2)} + 5^{(2)} - 2 (13) (5) cos (B)

tan (6 t) = 2

sin(2x)-sin(x)+cos(2x)+cos(x)=0

sin (2 x) - sin (x) + cos (2 x) + cos (x) = 0

(cos(x)=1)=(sec(x)=1)

(cos (x) = 1) = (sec (x) = 1)

cot(x/3)=(-1)/(sqrt(3))

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