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人気のある三角関数 >

cos(2x)=-0.4,-180<= x<= 180

解

cos (2 x) = - 0.4, - 18 0^{\circ} \leq x \leq 18 0^{\circ}

解

x = 0.99115 \dots, x = - 0.99115 \dots, x = 2.15043 \dots, x = - 2.15043 \dots

解答ステップ

cos (2 x) = - 0.4, - 18 0^{\circ} \leq x \leq 18 0^{\circ}

三角関数の逆数プロパティを適用する

cos (2 x) = - 0.4

以下の一般解

cos (2 x) = - 0.4

cos (x) = - a \Rightarrow x = arccos (- a) + 36 0^{\circ} n, x = - arccos (- a) + 36 0^{\circ} n

2 x = arccos (- 0.4) + 36 0^{\circ} n, 2 x = - arccos (- 0.4) + 36 0^{\circ} n

2 x = arccos (- 0.4) + 36 0^{\circ} n, 2 x = - arccos (- 0.4) + 36 0^{\circ} n

解く

2 x = arccos (- 0.4) + 36 0^{\circ} n : x = \frac{arccos ( - 0.4 )}{2} + 18 0^{\circ} n

2 x = arccos (- 0.4) + 36 0^{\circ} n

以下で両辺を割る

2

2 x = arccos (- 0.4) + 36 0^{\circ} n

以下で両辺を割る

2

\frac{2 x}{2} = \frac{arccos ( - 0.4 )}{2} + \frac{36 0 ^{\circ} n}{2}

簡素化

x = \frac{arccos ( - 0.4 )}{2} + 18 0^{\circ} n

x = \frac{arccos ( - 0.4 )}{2} + 18 0^{\circ} n

解く

2 x = - arccos (- 0.4) + 36 0^{\circ} n : x = - \frac{arccos ( - 0.4 )}{2} + 18 0^{\circ} n

2 x = - arccos (- 0.4) + 36 0^{\circ} n

以下で両辺を割る

2

2 x = - arccos (- 0.4) + 36 0^{\circ} n

以下で両辺を割る

2

\frac{2 x}{2} = - \frac{arccos ( - 0.4 )}{2} + \frac{36 0 ^{\circ} n}{2}

簡素化

x = - \frac{arccos ( - 0.4 )}{2} + 18 0^{\circ} n

x = - \frac{arccos ( - 0.4 )}{2} + 18 0^{\circ} n

x = \frac{arccos ( - 0.4 )}{2} + 18 0^{\circ} n, x = - \frac{arccos ( - 0.4 )}{2} + 18 0^{\circ} n

範囲の解答

- 18 0^{\circ} \leq x \leq 18 0^{\circ}

x = 0.99115 \dots, x = - 0.99115 \dots, x = 2.15043 \dots, x = - 2.15043 \dots

グラフ

人気の例

cos(x)=(-4)/(8/3 sqrt(3))

cos (x) = \frac{- 4}{\frac{8}{3} 3}

- 2 tan (x) + 6 = 8

2 sin (x) = 1.564

sin (x) = 0.08

sin (x) = 0.05