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受欢迎的三角函数 >

(6cos(x)-5sin(x))^2+11sin^2(x)=36

解答

(6 cos (x) - 5 sin (x))^{2} + 11 sin^{2} (x) = 36

解答

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

+1

度数

x = 9 0^{\circ} + 36 0^{\circ} n, x = 27 0^{\circ} + 36 0^{\circ} n, x = 0^{\circ} + 36 0^{\circ} n, x = 18 0^{\circ} + 36 0^{\circ} n

求解步骤

(6 cos (x) - 5 sin (x))^{2} + 11 sin^{2} (x) = 36

两边减去

36

36 cos^{2} (x) - 60 cos (x) sin (x) + 36 sin^{2} (x) - 36 = 0

使用三角恒等式改写

- 36 + 36 cos^{2} (x) + 36 sin^{2} (x) - 60 cos (x) sin (x)

使用毕达哥拉斯恒等式:

cos^{2} (x) + sin^{2} (x) = 1

cos^{2} (x) = 1 - sin^{2} (x)

= - 36 + 36 (1 - sin^{2} (x)) + 36 sin^{2} (x) - 60 cos (x) sin (x)

化简

- 36 + 36 (1 - sin^{2} (x)) + 36 sin^{2} (x) - 60 cos (x) sin (x) : - 60 cos (x) sin (x)

- 36 + 36 (1 - sin^{2} (x)) + 36 sin^{2} (x) - 60 cos (x) sin (x)

乘开

36 (1 - sin^{2} (x)) : 36 - 36 sin^{2} (x)

36 (1 - sin^{2} (x))

使用分配律:

a (b - c) = ab - a c

a = 36, b = 1, c = sin^{2} (x)

= 36 \cdot 1 - 36 sin^{2} (x)

数字相乘:

36 \cdot 1 = 36

= 36 - 36 sin^{2} (x)

= - 36 + 36 - 36 sin^{2} (x) + 36 sin^{2} (x) - 60 cos (x) sin (x)

化简

- 36 + 36 - 36 sin^{2} (x) + 36 sin^{2} (x) - 60 cos (x) sin (x) : - 60 cos (x) sin (x)

- 36 + 36 - 36 sin^{2} (x) + 36 sin^{2} (x) - 60 cos (x) sin (x)

同类项相加:

- 36 sin^{2} (x) + 36 sin^{2} (x) = 0

= - 36 + 36 - 60 cos (x) sin (x)

- 36 + 36 = 0

= - 60 cos (x) sin (x)

= - 60 cos (x) sin (x)

= - 60 cos (x) sin (x)

- 60 cos (x) sin (x) = 0

分别求解每个部分

cos (x) = 0 or sin (x) = 0

cos (x) = 0 : x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn

cos (x) = 0

cos (x) = 0

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

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

sin (x) = 0 : x = 2 πn, x = π + 2 πn

sin (x) = 0

sin (x) = 0

的通解

sin (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} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{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} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

x = 0 + 2 πn, x = π + 2 πn

x = 0 + 2 πn, x = π + 2 πn

解

x = 0 + 2 πn : x = 2 πn

x = 0 + 2 πn

0 + 2 πn = 2 πn

x = 2 πn

x = 2 πn, x = π + 2 πn

合并所有解

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

作图

流行的例子

(3cos(x)-6sin(x))^2-27sin^2(x)=-9

(3 cos (x) - 6 sin (x))^{2} - 27 sin^{2} (x) = - 9

3(cos(x)-sin(x))=0

3 (cos (x) - sin (x)) = 0

4tan(x)+4sqrt(3)=0

4 tan (x) + 43 = 0

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

sin (5 a) = 0