cos(θ)= 1/9

解答

cos (θ) = \frac{1}{9}

θ = 1.45945 \dots + 2 πn, θ = 2 π - 1.45945 \dots + 2 πn

度数

θ = 83.62062 \dots^{\circ} + 36 0^{\circ} n, θ = 276.37937 \dots^{\circ} + 36 0^{\circ} n

求解步骤

cos (θ) = \frac{1}{9}

使用反三角函数性质

cos (θ) = \frac{1}{9}

cos (θ) = \frac{1}{9}

的通解

cos (x) = a \Rightarrow x = arccos (a) + 2 πn, x = 2 π - arccos (a) + 2 πn

θ = arccos (\frac{1}{9}) + 2 πn, θ = 2 π - arccos (\frac{1}{9}) + 2 πn

θ = arccos (\frac{1}{9}) + 2 πn, θ = 2 π - arccos (\frac{1}{9}) + 2 πn

以小数形式表示解

θ = 1.45945 \dots + 2 πn, θ = 2 π - 1.45945 \dots + 2 πn

- 33 sin (v) + 3 cos (v) = 32

so l v e f or x, - arctan (y) = arctan (x)

10 cos (x) = 8

2 sin^{2} (x) = 6 cos^{2} (x)

so l v e f or x, r + s - 6 t = cos (2 x + y)