cos(θ)=-5/8

解答

cos (θ) = - \frac{5}{8}

θ = 2.24592 \dots + 2 πn, θ = - 2.24592 \dots + 2 πn

度数

θ = 128.68218 \dots^{\circ} + 36 0^{\circ} n, θ = - 128.68218 \dots^{\circ} + 36 0^{\circ} n

求解步骤

cos (θ) = - \frac{5}{8}

使用反三角函数性质

cos (θ) = - \frac{5}{8}

cos (θ) = - \frac{5}{8}

的通解

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

θ = arccos (- \frac{5}{8}) + 2 πn, θ = - arccos (- \frac{5}{8}) + 2 πn

θ = arccos (- \frac{5}{8}) + 2 πn, θ = - arccos (- \frac{5}{8}) + 2 πn

以小数形式表示解

θ = 2.24592 \dots + 2 πn, θ = - 2.24592 \dots + 2 πn

\frac{368.02}{sin ( 6 6 ^{\circ} - x )} = \frac{290}{sin ( 3 8 ^{\circ} )}

cos^{2} (x) sec (x) = 1

tan (x) = \frac{9.3}{7.5}

sin (α) + cos (α) = 1

2 sin (θ) = 3 tan (θ)