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受欢迎的三角函数 >

2/5 cos(x)=(sqrt(2))/5

解答

\frac{2}{5} cos (x) = \frac{2}{5}

解答

x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

+1

度数

x = 4 5^{\circ} + 36 0^{\circ} n, x = 31 5^{\circ} + 36 0^{\circ} n

求解步骤

\frac{2}{5} cos (x) = \frac{2}{5}

在两边乘以

5

\frac{2}{5} cos (x) = \frac{2}{5}

在两边乘以

5

5 \cdot \frac{2}{5} cos (x) = \frac{5 2}{5}

化简

2 cos (x) = 2

2 cos (x) = 2

两边除以

2

2 cos (x) = 2

两边除以

2

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

化简

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

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

cos (x) = \frac{2}{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{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

作图

流行的例子

sin^2(x)=6(cos(-x)+1)

sin^{2} (x) = 6 (cos (- x) + 1)

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

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

sin(θ)=-7/25 ,cos(θ/2),270<θ<360

sin (θ) = - \frac{7}{25}, cos (\frac{θ}{2}), 27 0^{\circ} < θ < 36 0^{\circ}

3cos((2pit)/3)+10=11

3 cos (\frac{2 π t}{3}) + 10 = 11

9 sec^{2} (x) - 9 = 0