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受欢迎的三角函数 >

3cos^2(x)+sin^2(x)=3

解答

3 cos^{2} (x) + sin^{2} (x) = 3

解答

x = 2 πn, x = π + 2 πn

+1

度数

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

求解步骤

3 cos^{2} (x) + sin^{2} (x) = 3

两边减去

3

3 cos^{2} (x) + sin^{2} (x) - 3 = 0

使用三角恒等式改写

- 3 + sin^{2} (x) + 3 cos^{2} (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)

= - 3 + sin^{2} (x) + 3 (1 - sin^{2} (x))

化简

- 3 + sin^{2} (x) + 3 (1 - sin^{2} (x)) : - 2 sin^{2} (x)

- 3 + sin^{2} (x) + 3 (1 - sin^{2} (x))

乘开

3 (1 - sin^{2} (x)) : 3 - 3 sin^{2} (x)

3 (1 - sin^{2} (x))

使用分配律:

a (b - c) = ab - a c

a = 3, b = 1, c = sin^{2} (x)

= 3 \cdot 1 - 3 sin^{2} (x)

数字相乘:

3 \cdot 1 = 3

= 3 - 3 sin^{2} (x)

= - 3 + sin^{2} (x) + 3 - 3 sin^{2} (x)

化简

- 3 + sin^{2} (x) + 3 - 3 sin^{2} (x) : - 2 sin^{2} (x)

- 3 + sin^{2} (x) + 3 - 3 sin^{2} (x)

对同类项分组

= sin^{2} (x) - 3 sin^{2} (x) - 3 + 3

同类项相加:

sin^{2} (x) - 3 sin^{2} (x) = - 2 sin^{2} (x)

= - 2 sin^{2} (x) - 3 + 3

- 3 + 3 = 0

= - 2 sin^{2} (x)

= - 2 sin^{2} (x)

= - 2 sin^{2} (x)

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

两边除以

- 2

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

两边除以

- 2

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

两边除以

- 2

\frac{- 2 sin ^{2} ( x )}{- 2} = \frac{0}{- 2}

化简

sin^{2} (x) = 0

sin^{2} (x) = 0

使用法则

x^{n} = 0 \Rightarrow x = 0

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

作图

流行的例子

4sin^2(x)+6sin(x)+2=0

4 sin^{2} (x) + 6 sin (x) + 2 = 0

sin^2(θ)+2-cos^2(θ)=3sin(θ)

sin^{2} (θ) + 2 - cos^{2} (θ) = 3 sin (θ)

sin(x)=sin^2(x)

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

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

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

tan^2(x)+2tan(x)+1=0

tan^{2} (x) + 2 tan (x) + 1 = 0